Add guards and implement basic cards

Assets/Battle/Targeting/OtherTargetPolicy.cs

@@ -0,0 +1,16 @@
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+public class OtherTargetPolicy: TargetingPolicy
+{
+    private BattleParticipant owner;
+
+    public OtherTargetPolicy(BattleParticipant owner) {
+        this.owner = owner;
+    }
+
+    public override bool CanTarget(BattleParticipant participant) {
+        return participant != this.owner;
+    }
+}