IMO it is better then Fel Reaver because you are not always able to answerMortuary Machine with minions, sometimes you must use spells instead. And if you are not able to answer possible magnetize, there will be incoming big face damage.
To be honest very strange epic cards this expansion... Very optional.
So here's the thing about this card. If Reborn IS good and IS played, then this card is very very powerful. Reborn is not stackable. So that means if everyone is playing Reborn, this card has zero downside.
But this is not likely, as not all classes will be playing Reborn minions. or enough to make you want to play this card.
For example if everyone played Mechs, then the Warrior 5 drop that does damage against all non-mechs, then that card would no longer be played by Warrior. We know that doesnt happen, and even in mirror matches, you will be playing non-mechs eventually.
This is the opposite and players will always have non-reborn minions. This card seems like a silence Priest archetype, which is alright. Then again, you could give your opponents Reborn, then steal them?