diff --git a/Mage/src/main/java/mage/game/combat/CombatGroup.java b/Mage/src/main/java/mage/game/combat/CombatGroup.java
index 350dfd4e6f6..c66dcd0c06d 100644
--- a/Mage/src/main/java/mage/game/combat/CombatGroup.java
+++ b/Mage/src/main/java/mage/game/combat/CombatGroup.java
@@ -302,7 +302,7 @@ public class CombatGroup implements Serializable, Copyable<CombatGroup> {
             Map<UUID, Integer> assigned = new HashMap<>();
             if (blocked) {
                 boolean excessDamageToDefender = true;
-                for (UUID blockerId : blockerOrder) {
+                for (UUID blockerId : new ArrayList<>(blockerOrder)) { // prevent ConcurrentModificationException
                     Permanent blocker = game.getPermanent(blockerId);
                     if (blocker != null) {
                         int lethalDamage;