diff --git a/core/src/effect.rs b/core/src/effect.rs
index 9c58f2b9..d65a518c 100644
--- a/core/src/effect.rs
+++ b/core/src/effect.rs
@@ -75,6 +75,7 @@ impl Effect {
         match self {
             Effect::Banish => true,
 
+            // delete sustain immunitiy???
             Effect::Sustain => [
                 Skill::Stun,
                 Skill::Silence,
@@ -198,7 +199,10 @@ impl Effect {
         }
     }
 
-    pub fn colour(&self) -> Option<Colour> {
+    // Old colour matching system for buffs / debuffs
+    // Had issues as some effects will be considered as both a buff and debuff e.g. invert, 
+    // Ended up being confusing with mismatch skills that have red / blue e.g. amplify, haste, hybrid
+/*    pub fn colour(&self) -> Option<Colour> {
         match self {
             // physical
             Effect::Stun => Some(Colour::Red),
@@ -245,5 +249,5 @@ impl Effect {
             Effect::Countered => None,
             Effect::Ko => None,
         }
-    }
+    }*/
 }
diff --git a/core/src/game.rs b/core/src/game.rs
index 8f7e01c8..f53b6700 100644
--- a/core/src/game.rs
+++ b/core/src/game.rs
@@ -1970,6 +1970,28 @@ mod tests {
         }));
     }
 
+    #[test]
+    fn sustain_test() {
+        // Standard case where construct gets ko from a big hit
+        let mut game = create_2v2_test_game();
+        let player = game.players[0].id;
+        let source = game.players[0].constructs[0].id;
+        let target = game.players[1].constructs[0].id;
+        game.players[0].constructs[0].red_power.force(1000000);
+        game.new_resolve(Cast::new(source, player, target, Skill::Attack));
+        assert!(game.players[1].constructs[0].is_ko() == true);
+
+        // Sustain case where construct survives
+        let mut game = create_2v2_test_game();
+        let player = game.players[0].id;
+        let source = game.players[0].constructs[0].id;
+        let target = game.players[1].constructs[0].id;
+        game.players[0].constructs[0].red_power.force(1000000);
+        game.new_resolve(Cast::new(source, player, target, Skill::Sustain));
+        game.new_resolve(Cast::new(source, player, target, Skill::Attack));
+        assert!(game.players[1].constructs[0].is_ko() == false);
+    }
+
     #[test]
     fn tick_consistency_test() {
         let mut game = create_test_game();