Sounds racist.
Anyway, Mori literally doesn't have the range to affect all of Medea. So he can't win this. Medea could just keep draining power from that and other universes until she eventually just kills him via brute force. She's almost multiverse level already.
One could also debate whether Medea's attacks need to "enter the universe" if she just makes it so that the whole universe never existed from outside the universe.
Also, if that Karmic Cycle thing just means events repeat forever, wouldn't Medea retroactively changing things so that he died since the first loop mean he dies forever? Like, if he is dead in all loops then it loops like the Karmic Cycle demands. Just that, against Mori's intention, it's his own death that loops. It doesn't seem like a good defense against an opponent that can alter every iteration of the cycle in the same fashion simultaneously. Idk, maybe I just don't get what that ability does.