Unicorns can now equip spells to their active and passive ability slots

src/main/java/com/minelittlepony/unicopia/ability/ChangelingDisguiseAbility.java

@@ -61,7 +61,7 @@ public class ChangelingDisguiseAbility extends ChangelingFeedAbility {
         player.getEntityWorld().playSound(null, player.getBlockPos(), SoundEvents.ENTITY_PARROT_IMITATE_RAVAGER, SoundCategory.PLAYERS, 1.4F, 0.4F);
 
         iplayer.getSpellSlot().get(SpellType.CHANGELING_DISGUISE, true)
-            .orElseGet(() -> SpellType.CHANGELING_DISGUISE.apply(iplayer, SpellTraits.EMPTY))
+            .orElseGet(() -> SpellType.CHANGELING_DISGUISE.withTraits().apply(iplayer))
             .setDisguise(looked);
 
         if (!player.isCreative()) {

src/main/java/com/minelittlepony/unicopia/ability/UnicornCastingAbility.java

@@ -4,14 +4,11 @@ import java.util.Random;
 
 import org.jetbrains.annotations.Nullable;
 
-import com.google.common.collect.Streams;
 import com.minelittlepony.unicopia.Race;
 import com.minelittlepony.unicopia.ability.data.Hit;
 import com.minelittlepony.unicopia.ability.magic.spell.effect.CustomisedSpellType;
-import com.minelittlepony.unicopia.ability.magic.spell.effect.SpellType;
 import com.minelittlepony.unicopia.entity.player.Pony;
 import com.minelittlepony.unicopia.item.AmuletItem;
-import com.minelittlepony.unicopia.item.GemstoneItem;
 import com.minelittlepony.unicopia.particle.MagicParticleEffect;
 
 import net.minecraft.item.ItemStack;
@@ -58,7 +55,7 @@ public class UnicornCastingAbility implements Ability<Hit> {
             return Hit.of(manaLevel > 0 && ((AmuletItem)amulet.getValue().getItem()).canCharge(amulet.getValue()));
         }
 
-        ActionResult spell = getNewSpell(player).getResult();
+        ActionResult spell = player.getCharms().getSpellInHand(Hand.MAIN_HAND).getResult();
 
         if (spell != ActionResult.PASS) {
             return Hit.of(spell != ActionResult.FAIL && manaLevel > 4F);
@@ -82,7 +79,7 @@ public class UnicornCastingAbility implements Ability<Hit> {
             return Math.min(manaLevel, ((AmuletItem)amulet.getValue().getItem()).getChargeRemainder(amulet.getValue()));
         }
 
-        if (getNewSpell(player).getResult() == ActionResult.CONSUME) {
+        if (player.getCharms().getSpellInHand(Hand.MAIN_HAND).getResult() == ActionResult.CONSUME) {
             return 4F;
         }
 
@@ -111,7 +108,7 @@ public class UnicornCastingAbility implements Ability<Hit> {
                 }
             }
         } else {
-            TypedActionResult<CustomisedSpellType<?>> newSpell = getNewSpell(player);
+            TypedActionResult<CustomisedSpellType<?>> newSpell = player.getCharms().getSpellInHand(Hand.MAIN_HAND);
 
             if (newSpell.getResult() != ActionResult.FAIL) {
                 CustomisedSpellType<?> spell = newSpell.getValue();
@@ -140,14 +137,6 @@ public class UnicornCastingAbility implements Ability<Hit> {
         return TypedActionResult.pass(stack);
     }
 
-    private TypedActionResult<CustomisedSpellType<?>> getNewSpell(Pony player) {
-        return Streams.stream(player.getMaster().getItemsHand())
-                .filter(GemstoneItem::isEnchanted)
-                .map(stack -> GemstoneItem.consumeSpell(stack, player.getMaster(), null, null))
-                .findFirst()
-                .orElse(TypedActionResult.<CustomisedSpellType<?>>pass(SpellType.SHIELD.withTraits()));
-    }
-
     @Override
     public void preApply(Pony player, AbilitySlot slot) {
         player.getMagicalReserves().getExhaustion().multiply(3.3F);

src/main/java/com/minelittlepony/unicopia/ability/UnicornProjectileAbility.java

@@ -1,17 +1,13 @@
 package com.minelittlepony.unicopia.ability;
 
-import org.jetbrains.annotations.Nullable;
-
-import com.google.common.collect.Streams;
 import com.minelittlepony.unicopia.Race;
 import com.minelittlepony.unicopia.ability.data.Hit;
 import com.minelittlepony.unicopia.ability.magic.spell.effect.CustomisedSpellType;
-import com.minelittlepony.unicopia.ability.magic.spell.effect.SpellType;
 import com.minelittlepony.unicopia.entity.player.Pony;
-import com.minelittlepony.unicopia.item.GemstoneItem;
 import com.minelittlepony.unicopia.particle.MagicParticleEffect;
 
 import net.minecraft.util.ActionResult;
+import net.minecraft.util.Hand;
 import net.minecraft.util.Identifier;
 import net.minecraft.util.TypedActionResult;
 
@@ -46,7 +42,7 @@ public class UnicornProjectileAbility implements Ability<Hit> {
 
     @Override
     public Hit tryActivate(Pony player) {
-        return Hit.of(getNewSpell(player).getResult() != ActionResult.FAIL);
+        return Hit.of(player.getCharms().getSpellInHand(Hand.OFF_HAND).getResult() != ActionResult.FAIL);
     }
 
     @Override
@@ -61,29 +57,14 @@ public class UnicornProjectileAbility implements Ability<Hit> {
 
     @Override
     public void apply(Pony player, Hit data) {
-        TypedActionResult<CustomisedSpellType<?>> thrown = getNewSpell(player);
+        TypedActionResult<CustomisedSpellType<?>> thrown = player.getCharms().getSpellInHand(Hand.OFF_HAND);
 
         if (thrown.getResult() != ActionResult.FAIL) {
-            @Nullable
-            CustomisedSpellType<?> spell = thrown.getValue();
-
-            if (spell == null) {
-                spell = SpellType.VORTEX.withTraits();
-            }
-
             player.subtractEnergyCost(getCostEstimate(player));
-            spell.create().toThrowable().throwProjectile(player);
+            thrown.getValue().create().toThrowable().throwProjectile(player);
         }
     }
 
-    private TypedActionResult<CustomisedSpellType<?>> getNewSpell(Pony player) {
-        return Streams.stream(player.getMaster().getItemsHand())
-                .filter(GemstoneItem::isEnchanted)
-                .map(stack -> GemstoneItem.consumeSpell(stack, player.getMaster(), null, null))
-                .findFirst()
-                .orElse(TypedActionResult.<CustomisedSpellType<?>>pass(null));
-    }
-
     @Override
     public void preApply(Pony player, AbilitySlot slot) {
         player.getMagicalReserves().getExhaustion().multiply(3.3F);

src/main/java/com/minelittlepony/unicopia/ability/magic/spell/ThrowableSpell.java

@@ -49,7 +49,7 @@ public final class ThrowableSpell extends AbstractDelegatingSpell {
         if (!caster.isClient()) {
             MagicProjectileEntity projectile = new MagicProjectileEntity(world, entity);
 
-            projectile.setItem(GemstoneItem.enchanted(UItems.GEMSTONE.getDefaultStack(), spell.getType()));
+            projectile.setItem(GemstoneItem.enchant(UItems.GEMSTONE.getDefaultStack(), spell.getType()));
             projectile.getSpellSlot().put(this);
             projectile.setVelocity(entity, entity.getPitch(), entity.getYaw(), 0, 1.5F, 1);
             projectile.setHydrophobic();

src/main/java/com/minelittlepony/unicopia/ability/magic/spell/crafting/TraitRequirementRecipe.java

@@ -74,7 +74,7 @@ public class TraitRequirementRecipe implements SpellbookRecipe {
 
         SpellType<?> spell = SpellType.getKey(Identifier.tryParse(JsonHelper.getString(json, "spell", "")));
         if (spell != SpellType.EMPTY_KEY) {
-            return GemstoneItem.enchanted(stack, spell);
+            return GemstoneItem.enchant(stack, spell);
         }
         return stack;
     }

src/main/java/com/minelittlepony/unicopia/ability/magic/spell/effect/CatapultSpell.java

@@ -71,7 +71,7 @@ public class CatapultSpell extends AbstractSpell implements ProjectileSpell {
         } else {
             e.addVelocity(
                 ((caster.getWorld().random.nextFloat() * HORIZONTAL_VARIANCE) - HORIZONTAL_VARIANCE + vel.x * 0.8F) * 0.1F,
-                0.1F + (getTraits().get(Trait.STRENGTH, -MAX_STRENGTH, MAX_STRENGTH) - 50) / 16D,
+                0.1F + (getTraits().get(Trait.STRENGTH, -MAX_STRENGTH, MAX_STRENGTH) - 40) / 16D,
                 ((caster.getWorld().random.nextFloat() * HORIZONTAL_VARIANCE) - HORIZONTAL_VARIANCE + vel.z * 0.8F) * 0.1F
             );
         }

src/main/java/com/minelittlepony/unicopia/ability/magic/spell/effect/CustomisedSpellType.java

@@ -7,14 +7,14 @@ import com.minelittlepony.unicopia.ability.magic.SpellPredicate;
 import com.minelittlepony.unicopia.ability.magic.spell.Spell;
 import com.minelittlepony.unicopia.ability.magic.spell.trait.SpellTraits;
 
-public class CustomisedSpellType<T extends Spell> implements SpellPredicate<T> {
+import net.minecraft.item.ItemStack;
-    private final SpellType<T> type;
+import net.minecraft.nbt.NbtCompound;
-    private final SpellTraits traits;
+import net.minecraft.util.TypedActionResult;
 
-    public CustomisedSpellType(SpellType<T> type, SpellTraits traits) {
+public record CustomisedSpellType<T extends Spell> (
-        this.type = type;
+        SpellType<T> type,
-        this.traits = traits;
+        SpellTraits traits
-    }
+        ) implements SpellPredicate<T> {
 
     public boolean isEmpty() {
         return type.isEmpty();
@@ -33,4 +33,26 @@ public class CustomisedSpellType<T extends Spell> implements SpellPredicate<T> {
     public boolean test(Spell spell) {
         return type.test(spell);
     }
+
+    public ItemStack getDefaultStack() {
+        return type.getDefualtStack();
+    }
+
+    public TypedActionResult<CustomisedSpellType<?>> toAction() {
+        return isEmpty() ? TypedActionResult.fail(this) : TypedActionResult.pass(this);
+    }
+
+    public NbtCompound toNBT() {
+        NbtCompound tag = new NbtCompound();
+        type.writeId(tag);
+        tag.put("traits", traits.toNbt());
+        return tag;
+    }
+
+    public static CustomisedSpellType<?> fromNBT(NbtCompound compound) {
+        SpellType<?> type = SpellType.getKey(compound);
+        SpellTraits traits = SpellTraits.fromNbt(compound.getCompound("traits")).orElse(type.getTraits());
+
+        return type.withTraits(traits);
+    }
 }

src/main/java/com/minelittlepony/unicopia/ability/magic/spell/effect/SpellType.java

@@ -20,8 +20,11 @@ import com.minelittlepony.unicopia.ability.magic.spell.PlaceableSpell;
 import com.minelittlepony.unicopia.ability.magic.spell.Spell;
 import com.minelittlepony.unicopia.ability.magic.spell.ThrowableSpell;
 import com.minelittlepony.unicopia.ability.magic.spell.trait.SpellTraits;
+import com.minelittlepony.unicopia.item.GemstoneItem;
+import com.minelittlepony.unicopia.item.UItems;
 import com.minelittlepony.unicopia.util.Registries;
 
+import net.minecraft.item.ItemStack;
 import net.minecraft.nbt.NbtCompound;
 import net.minecraft.text.Text;
 import net.minecraft.text.TranslatableText;
@@ -75,6 +78,8 @@ public final class SpellType<T extends Spell> implements Affine, SpellPredicate<
     private final CustomisedSpellType<T> traited;
     private final SpellTraits traits;
 
+    private final ItemStack defaultStack;
+
     private SpellType(Identifier id, Affinity affinity, int color, boolean obtainable, SpellTraits traits, Factory<T> factory) {
         this.id = id;
         this.affinity = affinity;
@@ -83,6 +88,7 @@ public final class SpellType<T extends Spell> implements Affine, SpellPredicate<
         this.factory = factory;
         this.traits = traits;
         traited = new CustomisedSpellType<>(this, traits);
+        defaultStack = GemstoneItem.enchant(UItems.GEMSTONE.getDefaultStack(), this);
     }
 
     public boolean isObtainable() {
@@ -93,6 +99,10 @@ public final class SpellType<T extends Spell> implements Affine, SpellPredicate<
         return id;
     }
 
+    public ItemStack getDefualtStack() {
+        return defaultStack;
+    }
+
     /**
      * Gets the tint for this spell when applied to a gem.
      */
@@ -182,9 +192,13 @@ public final class SpellType<T extends Spell> implements Affine, SpellPredicate<
         return (SpellType<T>)EMPTY_KEY;
     }
 
+    public static <T extends Spell> SpellType<T> getKey(NbtCompound tag) {
+        return getKey(Identifier.tryParse(tag.getString("effect_id")));
+    }
+
     @SuppressWarnings("unchecked")
-    public static <T extends Spell> SpellType<T> getKey(Identifier id) {
+    public static <T extends Spell> SpellType<T> getKey(@Nullable Identifier id) {
-        return (SpellType<T>)(EMPTY_ID.equals(id) ? EMPTY_KEY : REGISTRY.getOrEmpty(id).orElse(EMPTY_KEY));
+        return (SpellType<T>)(id == null || EMPTY_ID.equals(id) ? EMPTY_KEY : REGISTRY.getOrEmpty(id).orElse(EMPTY_KEY));
     }
 
     public static SpellType<?> random(Random random) {
@@ -198,7 +212,7 @@ public final class SpellType<T extends Spell> implements Affine, SpellPredicate<
     @Nullable
     public static Spell fromNBT(@Nullable NbtCompound compound) {
         if (compound != null && compound.contains("effect_id")) {
-            Spell effect = getKey(new Identifier(compound.getString("effect_id"))).create(SpellTraits.EMPTY);
+            Spell effect = getKey(compound).create(SpellTraits.EMPTY);
 
             if (effect != null) {
                 effect.fromNBT(compound);
@@ -212,12 +226,14 @@ public final class SpellType<T extends Spell> implements Affine, SpellPredicate<
 
     public static NbtCompound toNBT(Spell effect) {
         NbtCompound compound = effect.toNBT();
-
+        effect.getType().writeId(compound);
-        compound.putString("effect_id", effect.getType().getId().toString());
-
         return compound;
     }
 
+    public void writeId(NbtCompound tag) {
+        tag.putString("effect_id", getId().toString());
+    }
+
     public interface Factory<T extends Spell> {
         T create(SpellType<T> type, SpellTraits traits);
     }

src/main/java/com/minelittlepony/unicopia/ability/magic/spell/trait/SpellTraits.java

@@ -127,6 +127,16 @@ public final class SpellTraits implements Iterable<Map.Entry<Trait, Float>> {
         });
     }
 
+    @Override
+    public int hashCode() {
+        return traits.hashCode();
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        return this == other || other instanceof SpellTraits && Objects.equals(traits, ((SpellTraits) other).traits);
+    }
+
     public static SpellTraits union(SpellTraits...many) {
         Map<Trait, Float> traits = new HashMap<>();
         for (SpellTraits i : many) {

src/main/java/com/minelittlepony/unicopia/client/gui/UHud.java

@@ -10,6 +10,7 @@ import com.minelittlepony.unicopia.USounds;
 import com.minelittlepony.unicopia.ability.AbilityDispatcher;
 import com.minelittlepony.unicopia.ability.AbilitySlot;
 import com.minelittlepony.unicopia.ability.magic.spell.AbstractDisguiseSpell;
+import com.minelittlepony.unicopia.ability.magic.spell.effect.CustomisedSpellType;
 import com.minelittlepony.unicopia.ability.magic.spell.effect.SpellType;
 import com.minelittlepony.unicopia.client.KeyBindingsHandler;
 import com.minelittlepony.unicopia.client.sound.LoopingSoundInstance;
@@ -29,6 +30,7 @@ import net.minecraft.entity.EntityDimensions;
 import net.minecraft.entity.player.PlayerEntity;
 import net.minecraft.text.Text;
 import net.minecraft.util.Arm;
+import net.minecraft.util.Hand;
 import net.minecraft.util.Identifier;
 import net.minecraft.util.math.MathHelper;
 import net.minecraft.util.math.Quaternion;
@@ -42,6 +44,8 @@ public class UHud extends DrawableHelper {
 
     public static final int PRIMARY_SLOT_SIZE = 49;
 
+    private static final float EQUIPPED_GEMSTONE_SCALE = 0.7F;
+
     public TextRenderer font;
 
     final MinecraftClient client = MinecraftClient.getInstance();
@@ -82,15 +86,23 @@ public class UHud extends DrawableHelper {
         xDirection = client.player.getMainArm() == Arm.LEFT ? -1 : 1;
 
         matrices.push();
-        matrices.translate(((scaledWidth - 50) / 2) + (104 * xDirection), scaledHeight - 50, 0);
+
+        int hudX = ((scaledWidth - 50) / 2) + (104 * xDirection);
+        int hudY = scaledHeight - 50;
+        int hudZ = 0;
+
 
         float exhaustion = pony.getMagicalReserves().getExhaustion().getPercentFill();
 
         if (exhaustion > 0.5F) {
             Random rng = client.world.random;
-            matrices.translate(rng.nextFloat() - 0.5F, rng.nextFloat() - 0.5F, rng.nextFloat() - 0.5F);
+            hudX += rng.nextFloat() - 0.5F;
+            hudY += rng.nextFloat() - 0.5F;
+            hudZ += rng.nextFloat() - 0.5F;
         }
 
+        matrices.translate(hudX, hudY, hudZ);
+
         AbilityDispatcher abilities = pony.getAbilities();
 
         if (message != null && messageTime > 0) {
@@ -106,10 +118,15 @@ public class UHud extends DrawableHelper {
         slots.forEach(slot -> slot.renderBackground(matrices, abilities, swap, tickDelta));
         slots.forEach(slot -> slot.renderLabel(matrices, abilities, tickDelta));
 
-        RenderSystem.disableBlend();
-
         matrices.pop();
 
+        if (pony.getSpecies().canCast()) {
+            renderSpell(pony.getCharms().getEquippedSpell(Hand.MAIN_HAND), hudX + 15 - xDirection * 8, hudY + 2);
+            renderSpell(pony.getCharms().getEquippedSpell(Hand.OFF_HAND), hudX + 15 - xDirection * 0, hudY - 3);
+        }
+
+        RenderSystem.disableBlend();
+
         if (pony.getSpecies() == Race.CHANGELING && !client.player.isSneaking()) {
             pony.getSpellSlot().get(SpellType.CHANGELING_DISGUISE, false).map(AbstractDisguiseSpell::getDisguise)
                 .map(EntityAppearance::getAppearance)
@@ -137,15 +154,25 @@ public class UHud extends DrawableHelper {
         }
     }
 
-    private void renderMessage(MatrixStack matrices, float tickDelta) {
+    private void renderSpell(CustomisedSpellType<?> spell, int x, int y) {
+        if (!spell.isEmpty()) {
+            MatrixStack modelStack = RenderSystem.getModelViewStack();
+            modelStack.push();
+            modelStack.translate(x, y, 0);
+            modelStack.scale(EQUIPPED_GEMSTONE_SCALE, EQUIPPED_GEMSTONE_SCALE, EQUIPPED_GEMSTONE_SCALE);
+            RenderSystem.applyModelViewMatrix();
+            client.getItemRenderer().renderGuiItemIcon(spell.getDefaultStack(), 0, 0);
+            modelStack.pop();
+            RenderSystem.applyModelViewMatrix();
+        }
+    }
 
+    private void renderMessage(MatrixStack matrices, float tickDelta) {
         float time = messageTime - tickDelta;
         int progress = Math.min(255, (int)(time * 255F / 20F));
 
         if (progress > 8) {
-
             int color = 0xFFFFFF;
-
             int alpha = progress << 24 & -16777216;
 
             color |= alpha;
@@ -239,5 +266,4 @@ public class UHud extends DrawableHelper {
             RenderSystem.setShaderTexture(0, HUD_TEXTURE);
         });
     }
-
 }

src/main/java/com/minelittlepony/unicopia/command/DisguiseCommand.java

@@ -84,7 +84,7 @@ public class DisguiseCommand {
 
         Pony iplayer = Pony.of(player);
         iplayer.getSpellSlot().get(SpellType.CHANGELING_DISGUISE, true)
-            .orElseGet(() -> SpellType.CHANGELING_DISGUISE.apply(iplayer, SpellTraits.EMPTY))
+            .orElseGet(() -> SpellType.CHANGELING_DISGUISE.withTraits().apply(iplayer))
             .setDisguise(entity);
 
         if (source.getEntity() == player) {

src/main/java/com/minelittlepony/unicopia/entity/UTradeOffers.java

@@ -36,7 +36,7 @@ public interface UTradeOffers {
 
         TradeOfferHelper.registerWanderingTraderOffers(1, factories -> {
             factories.add(buyTiered(UItems.GEMSTONE, 30, UItems.GOLDEN_FEATHER, 1, UItems.GOLDEN_WING, 1, 30, 2, 0.05F));
-            factories.add((e, rng) -> new TradeOffer(new ItemStack(UItems.GEMSTONE, 3), GemstoneItem.enchanted(UItems.GEMSTONE.getDefaultStack(), SpellType.random(rng)), 20, 1, 0.05F));
+            factories.add((e, rng) -> new TradeOffer(new ItemStack(UItems.GEMSTONE, 3), GemstoneItem.enchant(UItems.GEMSTONE.getDefaultStack(), SpellType.random(rng)), 20, 1, 0.05F));
             factories.add(buy(UItems.GEMSTONE, 20, UItems.HAY_FRIES, 5, 50, 3, 0.06F));
             factories.add(buy(Items.WHEAT, 17, UItems.HAY_BURGER, 1, 10, 6, 0.08F));
             factories.add(buy(ItemTags.SMALL_FLOWERS, 2, UItems.DAFFODIL_DAISY_SANDWICH, 1, 10, 6, 0.08F));

src/main/java/com/minelittlepony/unicopia/entity/player/PlayerCharmTracker.java

@@ -7,14 +7,23 @@ import java.util.Objects;
 import java.util.Set;
 import java.util.stream.Stream;
 
+import com.google.common.collect.Streams;
 import com.minelittlepony.unicopia.ability.magic.Affine;
+import com.minelittlepony.unicopia.ability.magic.spell.effect.CustomisedSpellType;
+import com.minelittlepony.unicopia.ability.magic.spell.effect.SpellType;
+import com.minelittlepony.unicopia.item.GemstoneItem;
 import com.minelittlepony.unicopia.util.NbtSerialisable;
 import com.minelittlepony.unicopia.util.Tickable;
 
 import net.minecraft.item.ItemConvertible;
 import net.minecraft.item.ItemStack;
 import net.minecraft.nbt.NbtCompound;
+import net.minecraft.nbt.NbtElement;
+import net.minecraft.nbt.NbtList;
+import net.minecraft.sound.SoundEvents;
+import net.minecraft.util.Hand;
 import net.minecraft.util.Identifier;
+import net.minecraft.util.TypedActionResult;
 import net.minecraft.util.registry.Registry;
 
 public class PlayerCharmTracker implements Tickable, NbtSerialisable {
@@ -23,6 +32,11 @@ public class PlayerCharmTracker implements Tickable, NbtSerialisable {
 
     private final ItemTracker armour = new ItemTracker();
 
+    private CustomisedSpellType<?>[] handSpells = new CustomisedSpellType<?>[] {
+        SpellType.SHIELD.withTraits(),
+        SpellType.CATAPULT.withTraits()
+    };
+
     PlayerCharmTracker(Pony pony) {
         this.pony = pony;
     }
@@ -36,14 +50,47 @@ public class PlayerCharmTracker implements Tickable, NbtSerialisable {
         return armour;
     }
 
+    public CustomisedSpellType<?>[] getHandSpells() {
+        return handSpells;
+    }
+
+    public CustomisedSpellType<?> getEquippedSpell(Hand hand) {
+        return handSpells[hand.ordinal()];
+    }
+
+    public TypedActionResult<CustomisedSpellType<?>> getSpellInHand(Hand hand) {
+        return Streams.stream(pony.getMaster().getItemsHand())
+                .filter(GemstoneItem::isEnchanted)
+                .map(stack -> GemstoneItem.consumeSpell(stack, pony.getMaster(), null))
+                .findFirst()
+                .orElse(getEquippedSpell(hand).toAction());
+    }
+
+    public void equipSpell(Hand hand, CustomisedSpellType<?> spell) {
+        handSpells[hand.ordinal()] = spell;
+        pony.getMaster().playSound(SoundEvents.UI_BUTTON_CLICK, 0.25F, 1.75F);
+        pony.setDirty();
+    }
+
     @Override
     public void toNBT(NbtCompound compound) {
         compound.put("armour", armour.toNBT());
+        NbtList equippedSpells = new NbtList();
+        for (CustomisedSpellType<?> spell : handSpells) {
+            equippedSpells.add(spell.toNBT());
+        }
+        compound.put("handSpells", equippedSpells);
     }
 
     @Override
     public void fromNBT(NbtCompound compound) {
         armour.fromNBT(compound.getCompound("armour"));
+        if (compound.contains("handSpells", NbtElement.LIST_TYPE)) {
+            NbtList list = compound.getList("handSpells", NbtElement.COMPOUND_TYPE);
+            for (int i = 0; i < handSpells.length && i < list.size(); i++) {
+                handSpells[i] = CustomisedSpellType.fromNBT(list.getCompound(i));
+            }
+        }
     }
 
     public class ItemTracker implements NbtSerialisable {

src/main/java/com/minelittlepony/unicopia/entity/player/Pony.java

@@ -59,6 +59,7 @@ import net.minecraft.server.network.ServerPlayerEntity;
 import net.minecraft.server.world.ServerWorld;
 import net.minecraft.text.Text;
 import net.minecraft.text.TranslatableText;
+import net.minecraft.util.Hand;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.Direction;
 
@@ -511,6 +512,8 @@ public class Pony extends Living<PlayerEntity> implements Transmittable, Copieab
         oldPlayer.getSpellSlot().put(null);
         setSpecies(oldPlayer.getSpecies());
         getDiscoveries().copyFrom(oldPlayer.getDiscoveries());
+        getCharms().equipSpell(Hand.MAIN_HAND, oldPlayer.getCharms().getEquippedSpell(Hand.MAIN_HAND));
+        getCharms().equipSpell(Hand.OFF_HAND, oldPlayer.getCharms().getEquippedSpell(Hand.OFF_HAND));
         setDirty();
     }
 

src/main/java/com/minelittlepony/unicopia/item/GemstoneItem.java

@@ -1,7 +1,6 @@
 package com.minelittlepony.unicopia.item;
 
 import java.util.List;
-import java.util.Objects;
 import java.util.function.Predicate;
 
 import org.jetbrains.annotations.Nullable;
@@ -12,6 +11,8 @@ import com.minelittlepony.unicopia.ability.magic.spell.Spell;
 import com.minelittlepony.unicopia.ability.magic.spell.effect.CustomisedSpellType;
 import com.minelittlepony.unicopia.ability.magic.spell.effect.SpellType;
 import com.minelittlepony.unicopia.ability.magic.spell.trait.SpellTraits;
+import com.minelittlepony.unicopia.entity.player.PlayerCharmTracker;
+import com.minelittlepony.unicopia.entity.player.Pony;
 
 import net.minecraft.client.item.TooltipContext;
 import net.minecraft.entity.player.PlayerEntity;
@@ -34,6 +35,24 @@ public class GemstoneItem extends Item {
         super(settings);
     }
 
+    @Override
+    public TypedActionResult<ItemStack> use(World world, PlayerEntity user, Hand hand) {
+        TypedActionResult<ItemStack> result = super.use(world, user, hand);
+
+        if (!result.getResult().isAccepted()) {
+            ItemStack stack = user.getStackInHand(hand);
+            PlayerCharmTracker charms = Pony.of(user).getCharms();
+
+            TypedActionResult<CustomisedSpellType<?>> spell = consumeSpell(stack, user, ((Predicate<CustomisedSpellType<?>>)charms.getEquippedSpell(hand)::equals).negate());
+            if (spell.getResult().isAccepted()) {
+                charms.equipSpell(hand, spell.getValue());
+                return TypedActionResult.success(stack, true);
+            }
+        }
+
+        return result;
+    }
+
     @Override
     public void appendTooltip(ItemStack stack, @Nullable World world, List<Text> lines, TooltipContext tooltipContext) {
         super.appendTooltip(stack, world, lines, tooltipContext);
@@ -58,7 +77,7 @@ public class GemstoneItem extends Item {
             for (Affinity i : Affinity.VALUES) {
                 SpellType.byAffinity(i).forEach(type -> {
                     if (type.isObtainable()) {
-                        items.add(enchanted(getDefaultStack(), type, i));
+                        items.add(enchant(getDefaultStack(), type, i));
                     }
                 });
             }
@@ -82,20 +101,21 @@ public class GemstoneItem extends Item {
         return super.getName();
     }
 
-    public static TypedActionResult<CustomisedSpellType<?>> consumeSpell(ItemStack stack, PlayerEntity player, @Nullable SpellType<?> exclude, @Nullable Predicate<SpellType<?>> test) {
+    public static TypedActionResult<CustomisedSpellType<?>> consumeSpell(ItemStack stack, PlayerEntity player, @Nullable Predicate<CustomisedSpellType<?>> filter) {
 
         if (!isEnchanted(stack)) {
             return TypedActionResult.pass(null);
         }
 
         SpellType<Spell> key = getSpellKey(stack);
-        SpellTraits traits = SpellTraits.of(stack);
 
-        if (Objects.equals(key, exclude)) {
+        if (key.isEmpty()) {
             return TypedActionResult.fail(null);
         }
 
-        if (key.isEmpty() || (test != null && !test.test(key))) {
+        CustomisedSpellType<?> result = key.withTraits(SpellTraits.of(stack));
+
+        if (filter != null && !filter.test(result)) {
             return TypedActionResult.fail(null);
         }
 
@@ -103,29 +123,29 @@ public class GemstoneItem extends Item {
             player.swingHand(player.getStackInHand(Hand.OFF_HAND) == stack ? Hand.OFF_HAND : Hand.MAIN_HAND);
 
             if (stack.getCount() == 1) {
-                unenchanted(stack);
+                unenchant(stack);
             } else {
-                player.giveItemStack(unenchanted(stack.split(1)));
+                player.giveItemStack(unenchant(stack.split(1)));
             }
         }
 
-        return TypedActionResult.consume(key.withTraits(traits));
+        return TypedActionResult.consume(result);
     }
 
     public static boolean isEnchanted(ItemStack stack) {
         return !stack.isEmpty() && stack.hasNbt() && stack.getNbt().contains("spell");
     }
 
-    public static ItemStack enchanted(ItemStack stack, SpellType<?> type) {
+    public static ItemStack enchant(ItemStack stack, SpellType<?> type) {
-        return enchanted(stack, type, type.getAffinity());
+        return enchant(stack, type, type.getAffinity());
     }
 
-    public static ItemStack enchanted(ItemStack stack, SpellType<?> type, Affinity affinity) {
+    public static ItemStack enchant(ItemStack stack, SpellType<?> type, Affinity affinity) {
         stack.getOrCreateNbt().putString("spell", type.getId().toString());
         return type.getTraits().applyTo(stack);
     }
 
-    public static ItemStack unenchanted(ItemStack stack) {
+    public static ItemStack unenchant(ItemStack stack) {
         stack.removeSubNbt("spell");
         return stack;
     }

src/main/java/com/minelittlepony/unicopia/util/NbtSerialisable.java

@@ -15,18 +15,14 @@ public interface NbtSerialisable {
      *
      * @param compound  Compound tag to write to.
      */
-    default void toNBT(NbtCompound compound) {
+    void toNBT(NbtCompound compound);
-
-    }
 
     /**
      * Called to load this state from nbt
      *
      * @param compound  Compound tag to read from.
      */
-    default void fromNBT(NbtCompound compound) {
+    void fromNBT(NbtCompound compound);
-
-    }
 
     default NbtCompound toNBT() {
         NbtCompound compound = new NbtCompound();