Let’s come up with a monster.

Well, just say that a unit like Death is actually quite good... :)

Firstly, angels are already hated by demons there; secondly, it's not very good – for 3 heroes, only "In the Wake of Gods" could possibly come out now, but I don't play it and don't discuss it – it's better to consult with Saruman or fans of the third game.
And there are a lot of abilities!