[MOM] Implement Ancient Imperiosaur

Mage/src/main/java/mage/abilities/dynamicvalue/common/ConvokedSourceCount.java

@@ -0,0 +1,41 @@
+package mage.abilities.dynamicvalue.common;
+
+import mage.MageObjectReference;
+import mage.abilities.Ability;
+import mage.abilities.dynamicvalue.DynamicValue;
+import mage.abilities.effects.Effect;
+import mage.game.Game;
+import mage.watchers.common.ConvokeWatcher;
+
+/**
+ * @author TheElk801
+ */
+public enum ConvokedSourceCount implements DynamicValue {
+    PERMANENT(-1),
+    SPELL(0);
+    private final int offset;
+
+    ConvokedSourceCount(int offset) {
+        this.offset = offset;
+    }
+
+    @Override
+    public int calculate(Game game, Ability sourceAbility, Effect effect) {
+        return ConvokeWatcher.getConvokingCreatures(new MageObjectReference(sourceAbility, offset), game).size();
+    }
+
+    @Override
+    public ConvokedSourceCount copy() {
+        return this;
+    }
+
+    @Override
+    public String getMessage() {
+        return "creature that convoked it";
+    }
+
+    @Override
+    public String toString() {
+        return "1";
+    }
+}