Some changes to the convoke ability.

Mage.Sets/src/mage/sets/futuresight/KavuPrimarch.java

@@ -54,7 +54,7 @@ public class KavuPrimarch extends CardImpl<KavuPrimarch> {
         this.toughness = new MageInt(3);
 
         // Convoke (Each creature you tap while casting this spell reduces its cost by {1} or by one mana of that creature's color.)
-        this.addAbility(ConvokeAbility.getInstance());
+        this.addAbility(new ConvokeAbility());
 
         // Kicker {4} (You may pay an additional {4} as you cast this spell.)
         this.getSpellAbility().addOptionalCost(new KickerManaCost("{4}"));

Mage.Sets/src/mage/sets/ravnika/AutochthonWurm.java

@@ -58,7 +58,7 @@ public class AutochthonWurm extends CardImpl<AutochthonWurm> {
         this.toughness = new MageInt(14);
 
         // Convoke (Each creature you tap while casting this spell reduces its cost by {1} or by one mana of that creature's color.)
-        this.addAbility(ConvokeAbility.getInstance());
+        this.addAbility(new ConvokeAbility());
 
         // Trample
         this.addAbility(TrampleAbility.getInstance());

Mage.Sets/src/mage/sets/ravnika/Overwhelm.java

@@ -46,7 +46,7 @@ public class Overwhelm extends CardImpl<Overwhelm> {
       this.expansionSetCode = "RAV";
 
       // Convoke (Each creature you tap while casting this spell reduces its cost by {1} or by one mana of that creature's color.)
-      this.addAbility(ConvokeAbility.getInstance());
+      this.addAbility(new ConvokeAbility());
 
       // Creatures you control get +3/+3 until end of turn.
       this.getSpellAbility().addEffect(new BoostControlledEffect(3, 3, Duration.EndOfTurn));

Mage/src/mage/abilities/keyword/ConvokeAbility.java

@@ -88,31 +88,23 @@ import mage.util.CardUtil;
 
 public class ConvokeAbility extends SimpleStaticAbility implements AdjustingSourceCosts {
 
-    private static ConvokeAbility fINSTANCE =  new ConvokeAbility();
     private static final FilterControlledCreaturePermanent filter = new FilterControlledCreaturePermanent();
     static {
       filter.add(Predicates.not(new TappedPredicate()));
     }
 
-    private ConvokeAbility() {
+    public ConvokeAbility() {
         super(Zone.STACK, null);
         this.setRuleAtTheTop(true);
     }
 
-    public static ConvokeAbility getInstance() {
-        if (fINSTANCE == null) {
-            fINSTANCE = new ConvokeAbility();
-        }
-        return fINSTANCE;
-    }
-
     public ConvokeAbility(final ConvokeAbility ability) {
       super(ability);
     }
 
     @Override
-    public SimpleStaticAbility copy() {
-      return fINSTANCE;
+    public ConvokeAbility copy() {
+      return new ConvokeAbility(this);
     }
 
     @Override