Lemme help you here though, under no circumstances should you rank up karnak.
He’s used by the game to punish you for expecting a good champ from your crystal.
Oh yes, I would never get him to higher ranks. I was looking to upgrade my 4* Aegon, apparently didn't have enough t2 skill, and saw at the same time that Karnak was ready to go. Opening the upgrade tab, showed me this
Comments
https://forums.playcontestofchampions.com/en/discussion/220878/karnak-rank-up-issue-see-in-screenshot
or
https://forums.playcontestofchampions.com/en/discussion/183030/is-karnak-glitched-out
He’s used by the game to punish you for expecting a good champ from your crystal.