Fixed mana cost for cast spells not being passed on to the player

src/main/java/com/minelittlepony/unicopia/ability/magic/Caster.java

@@ -15,7 +15,6 @@ import com.minelittlepony.unicopia.util.VecHelper;
 
 import net.minecraft.entity.Entity;
 import net.minecraft.entity.LivingEntity;
-import net.minecraft.entity.damage.DamageSource;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.Vec3d;
 import net.minecraft.world.World;
@@ -63,10 +62,10 @@ public interface Caster<E extends LivingEntity> extends Owned<E>, Levelled, Affi
         return getEntity().getBlockPos();
     }
 
-    default boolean subtractEnergyCost(double amount) {
+    /**
-        getMaster().damage(DamageSource.MAGIC, (int)amount/2);
+     * Removes the desired amount of mana or health from this caster in exchange for a spell's benefits.
-        return getMaster().getHealth() > 0;
+     */
-    }
+    boolean subtractEnergyCost(double amount);
 
     default Stream<Caster<?>> findAllSpellsInRange(double radius) {
         return findAllSpellsInRange(radius, null);

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

@@ -145,6 +145,11 @@ public class CastSpellEntity extends Entity implements Caster<LivingEntity> {
         return Caster.of(getMaster()).map(Caster::getSpellSlot).orElse(SpellContainer.EMPTY);
     }
 
+    @Override
+    public boolean subtractEnergyCost(double amount) {
+        return Caster.of(getMaster()).filter(c -> c.subtractEnergyCost(amount)).isPresent();
+    }
+
     @Override
     protected void writeCustomDataToTag(CompoundTag tag) {
         tag.put("owner", owner.toNBT());

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

@@ -15,6 +15,7 @@ import net.minecraft.entity.SpawnGroup;
 import net.minecraft.entity.ai.goal.GoalSelector;
 import net.minecraft.entity.attribute.DefaultAttributeContainer;
 import net.minecraft.entity.attribute.EntityAttributes;
+import net.minecraft.entity.damage.DamageSource;
 import net.minecraft.entity.data.DataTracker;
 import net.minecraft.entity.data.TrackedData;
 import net.minecraft.entity.data.TrackedDataHandlerRegistry;
@@ -78,6 +79,12 @@ public class Creature extends Living<LivingEntity> {
         return LEVELS;
     }
 
+    @Override
+    public boolean subtractEnergyCost(double amount) {
+        getMaster().damage(DamageSource.MAGIC, (int)amount/2);
+        return getMaster().getHealth() > 0;
+    }
+
     @Override
     public Affinity getAffinity() {
         if (getMaster() instanceof Affine) {

src/main/java/com/minelittlepony/unicopia/projectile/MagicProjectileEntity.java

@@ -121,6 +121,11 @@ public class MagicProjectileEntity extends ThrownItemEntity implements Magical,
         return effectDelegate;
     }
 
+    @Override
+    public boolean subtractEnergyCost(double amount) {
+        return Caster.of(getMaster()).filter(c -> c.subtractEnergyCost(amount)).isPresent();
+    }
+
     public void setThrowDamage(float damage) {
         getDataTracker().set(DAMAGE, Math.max(0, damage));
     }