diff --git a/res/cardsfolder/harbor_serpent.txt b/res/cardsfolder/harbor_serpent.txt
index 75f382bb754..8db13f170d1 100644
--- a/res/cardsfolder/harbor_serpent.txt
+++ b/res/cardsfolder/harbor_serpent.txt
@@ -4,6 +4,7 @@ Types:Creature Serpent
 Text:Harbor Serpent can't attack unless there are five or more Islands on the battlefield.
 PT:5/5
 K:Islandwalk
+K:SVar:BuffedBy:Island
 K:SVar:Rarity:Common
 K:SVar:Picture:http://www.wizards.com/global/images/magic/general/harbor_serpent.jpg
 End
diff --git a/src/forge/CardFactory.java b/src/forge/CardFactory.java
index 4fe8f7af071..bb9845c2b47 100644
--- a/src/forge/CardFactory.java
+++ b/src/forge/CardFactory.java
@@ -5038,7 +5038,8 @@ public class CardFactory implements NewConstants {
                     	if (NumDefense[0] < 0 && !list.isEmpty()) { // with spells that give -X/-X, compi will try to destroy a creature
                     		list = list.filter(new CardListFilter() {
                                 public boolean addCard(Card c) {
-                                    return (c.getKillDamage() <= -NumDefense[0]);
+                                	if (c.getNetDefense() <= -NumDefense[0] ) return true; // can kill indestructible creatures
+                                    return (c.getKillDamage() <= -NumDefense[0] && !c.hasKeyword("Indestructible"));
                                 }
                         	}); // leaves all creatures that will be destroyed
                     	} // -X/-X end