So, I'll take the bait and assume the 4 cards spoiled today are for real.
Yahenni's Expertise called my attention, since we recently had a card with a similar mechanic make its way into Vintage. I'm not comparing Dark Petition's power with Expertise, and I feel Expertise is at best a meta or sideboard card. But isn't a Wrath that can also play your Mentor right after, for free, just great? I say Mentor but whatever, Walk, Recall, Will it has no color restriction like Petition.
My problem with it is that it does nothing against larger Eldrazi, specially TKS. Also, Esper Mentor is not a deck right now, so the card has no place that I can point to. I mean, can this even be a sideboard card for Storm? But the card is powerful enough imo to grant attention.
For anyone not aware of what it is:
All creatures get -3/-3 until end of turn.
You may cast a card with cmc 3 or less from your hand without paying its mana cost.