diff --git a/worlds/yugioh06/__init__.py b/worlds/yugioh06/__init__.py
index d14f839e2099..c8daf4f395fc 100644
--- a/worlds/yugioh06/__init__.py
+++ b/worlds/yugioh06/__init__.py
@@ -113,17 +113,17 @@ class Yugioh06World(World):
     for k, v in Required_Cards.items():
         location_name_to_id[k] = v + start_id
 
-    item_name_groups = {
-        "Core Booster": core_booster,
-        "Campaign Boss Beaten": ["Tier 1 Beaten", "Tier 2 Beaten", "Tier 3 Beaten", "Tier 4 Beaten", "Tier 5 Beaten"],
-        "Challenge": challenges,
-        "Tier 1 Opponent": tier_1_opponents,
-        "Tier 2 Opponent": tier_2_opponents,
-        "Tier 3 Opponent": tier_3_opponents,
-        "Tier 4 Opponent": tier_4_opponents,
-        "Tier 5 Opponent": tier_5_opponents,
-        "Campaign Opponent": tier_1_opponents + tier_2_opponents + tier_3_opponents +
-                             tier_4_opponents + tier_5_opponents
+    item_name_groups: Dict[str, Set[str]] = {
+        "Core Booster": set(core_booster),
+        "Campaign Boss Beaten": {"Tier 1 Beaten", "Tier 2 Beaten", "Tier 3 Beaten", "Tier 4 Beaten", "Tier 5 Beaten"},
+        "Challenge": set(challenges),
+        "Tier 1 Opponent": set(tier_1_opponents),
+        "Tier 2 Opponent": set(tier_2_opponents),
+        "Tier 3 Opponent": set(tier_3_opponents),
+        "Tier 4 Opponent": set(tier_4_opponents),
+        "Tier 5 Opponent": set(tier_5_opponents),
+        "Campaign Opponent": set(tier_1_opponents + tier_2_opponents + tier_3_opponents +
+                             tier_4_opponents + tier_5_opponents)
     }
 
     removed_challenges: List[str]