Dormammu & UmarvsTeam Satana

Dormammu & Umar Mephisto, Hela and other Hell-Lords were barely able to beat Dormammu, in MEPHISTO's own realm, and even then, it was not because of sheer power, but tactic, this should tell you how powerful he is even when he's not in his domain. Zarathos was already beaten by Dormammu's servant, toss in Umar, the duo stomps with ease.

Dormammu & Umar Dormammu and Umar = Best siblings