diff --git a/src/data/ability.ts b/src/data/ability.ts
index 51539d831d1..6edfa25a9c5 100644
--- a/src/data/ability.ts
+++ b/src/data/ability.ts
@@ -6275,7 +6275,8 @@ export function initAbilities() {
     new Ability(Abilities.SHARPNESS, 9)
       .attr(MovePowerBoostAbAttr, (user, target, move) => move.hasFlag(MoveFlags.SLICING_MOVE), 1.5),
     new Ability(Abilities.SUPREME_OVERLORD, 9)
-      .attr(VariableMovePowerBoostAbAttr, (user, target, move) => 1 + 0.1 * Math.min(user.isPlayer() ? globalScene.arena.playerFaints : globalScene.currentBattle.enemyFaints, 5)),
+      .attr(VariableMovePowerBoostAbAttr, (user, target, move) => 1 + 0.1 * Math.min(user.isPlayer() ? globalScene.arena.playerFaints : globalScene.currentBattle.enemyFaints, 5))
+      .partial(), // Should only boost once, on summon
     new Ability(Abilities.COSTAR, 9)
       .attr(PostSummonCopyAllyStatsAbAttr),
     new Ability(Abilities.TOXIC_DEBRIS, 9)