While impressive, Dormammu one ups even that. He's battled multiversal level beings and even managed to beat Eternity the embodiment of time and a multiversal reality warper once although he lost once as well. He's also is more powerful then Classic Doctor Strange who at his peak could bring the destructing of several universes at once. He's considered above Mephisto, an incarnation of Satan and has done things like overrule even Odin's enchantments (Odin being universal himself). And within his own dimension, he reigns supreme and even most Elder Gods (universal level+ beings) and powerless against him there.