Spells can now request an update by setting themselves as dirty on the server

src/main/java/com/minelittlepony/unicopia/network/EffectSync.java

@@ -42,11 +42,12 @@ public class EffectSync<T extends EntityLivingBase> {
             if (effect == null || !effect.getName().contentEquals(id)) {
                 if (effect != null) {
                     effect.setDead();
-                    effect = null;
                 }
                 effect = SpellRegistry.instance().createEffectFromNBT(comp);
             } else if (owned.getEntity().world.isRemote) {
                 effect.readFromNBT(comp);
+            } else if (effect.isDirty()) {
+                set(effect);
             }
         }
 

src/main/java/com/minelittlepony/unicopia/spell/AbstractSpell.java

@@ -4,7 +4,8 @@ import net.minecraft.nbt.NBTTagCompound;
 
 public abstract class AbstractSpell implements IMagicEffect {
 
-	protected boolean isDead = false;
+	protected boolean isDead;
+	protected boolean isDirty;
 
 	private int strength = 0;
 
@@ -33,6 +34,16 @@ public abstract class AbstractSpell implements IMagicEffect {
 		return isDead;
 	}
 
+    @Override
+    public boolean isDirty() {
+        return isDirty;
+    }
+
+    @Override
+    public void setDirty(boolean dirty) {
+        isDirty = dirty;
+    }
+
     @Override
     public void writeToNBT(NBTTagCompound compound) {
         compound.setBoolean("dead", isDead);
@@ -41,6 +52,7 @@ public abstract class AbstractSpell implements IMagicEffect {
 
     @Override
     public void readFromNBT(NBTTagCompound compound) {
+        setDirty(false);
         isDead = compound.getBoolean("dead");
         strength = compound.getInteger("spell_strength");
     }

src/main/java/com/minelittlepony/unicopia/spell/IMagicEffect.java

@@ -27,6 +27,16 @@ public interface IMagicEffect extends InbtSerialisable, ILevelled, IAligned {
 	 */
 	boolean getDead();
 
+    /**
+     * Returns true if this effect has changes that need to be sent to the client.
+     */
+    boolean isDirty();
+
+    /**
+     * Marks this effect as dirty.
+     */
+    void setDirty(boolean dirty);
+
 	/**
 	 * Returns true if this effect can be crafted into a gem.
 	 */