Fell into that trap with Mephisto on the Daily. Y'know, the one where if you knock him down to zero on his life-bar too soon and your guys keep doing counter-attacks, he can just re-up and attack you forever. Had to exit out of the game.
I just figured this was a thing.
Actually I don't know the one. What trap? I've never had a problem with him before, and I've battled him dozens of times. I don't find him that difficult at all. Who are you using?
I tend to use Black Panther and Hawkeye along with my agent. They more than take care of everyone (I usually fight Baron Mordo in the first wave).
The trick also is to know what their moves will be.
1st move: For both succubi: Temptation - so don't attack them then.
1st and 2nd move: For M - binding contract - for both of his minions
So you can attack M during this time, especially if you go first. Hawkeye always goes first for me because of some UISO he has.
Black Panther also has 3 goes against M because some UISO makes his 4th action a quick action, and then he gets an extra go as he's a tactician
And my agent gets 3 goes too (if she's playing as a tactician) because her hallowed axe is a quick action, and then she gets the bonus turn
So if all my heroes go first, that's 8 possible turns they take before any of the enemies strike.
If you reduce M's health down to zero, he always calls in his binding contract and one of his minions immediately dies while M is restored to full health.
The trick is to also target his minions so that M can only really do this once. But even if he does do it twice, it still shouldn't be that difficult to survive against him at all. I have never found that he attacks you forever.