Despite the burning oil and chapel geist, I'm not convinced we're white, and the wolf is a premium two drop. But whatever our second color is, we're going to be Rx, so we won't want many off-color low-drops.
I'm really not interested in picking up another 5 drop for our aggressive deck. Our second color is still up in the air and Darkthicket Wolf is a very high impact two drop, which is what our deck wants.
I'm interested in the wolf too, but not so much that I'll pass up on a strong on-color card. Both the scourge and the devils would fit, but the scourge is a bit more aggressive...
As far as curve considerations go, another five isn't the end of the world. We're actually doing a good job keeping a balanced curve so far, and until that changes I'll give the nod to powerful, on-color cards.
Crossway vampire is sooo good. The only strike against it is trying to jam it into Wr or Gr decks without the mana base to support it. Here, we're likely playing 12-14 mountains, and it's always going to come out on curve.
Also, this card is great in multiples (I'd play eight if I could). Let's see if we can't grab another. It's an upgrade over all our other three's besides the wolf.
Reckless Waif really is that good. T1 one the play, it is almost guaranteed to flip. It's good for about six points of damage a game, before it trades up on mana. One of the reasons to be red in triple INN, IMO.
The kessig wolf is good, but we already have four three-drops. So it's a worse card and a lower priority slot in our curve.
Waif is great on turn 1, but it's far more likely, that it comes down much later, and then it's mediocre at best. I'm pessimistic that way. Kessig Wolf has far better mid and late game potential and also fits well into the deck.