v.118 - Champions Update Highlights

It'll be 1,009,999 if it's the same secondary potential KMS got during Tempest, thanks to "데미지 최대값 : +#incMaxDamage" which adds +10,000 max damage (not on range). I'm not sure if there's higher since the highest I saw in extractions was 10k.

Hero's Hyperskill adds another 50k, if I'm not mistaken.
EDIT: Guess I had it right:

Epic Adventure : A buff that gives the legendary Adventurers of the Maple World 10% increased damage and the ability to pass the damage cap by 50,000 for 60 seconds. There is a cooldown of 120 seconds.