I suppose we will see. There’s really not much self damage Priest has that is good outside of aggro decks. And those are extremely limited and currently see no play in most Control Priest decks.
While Priest has healing to counteract to get to 42, that healing is counterintuitive at the same time. If you’re at 23 and the opponent is at 12 and you heal yourself to 30 so you can meet the 42, all you really did was what? Go to 42 health for 4+ mana and your opponent is still low on health. You didn’t really turn the tide of the battle. You just did a win more.
If you’re at 6 health and opponent is at 30 and you heal for 6 to get to 42 then play this…what did you really do? You were already losing the game pretty bad…unless you were facing an aggro deck, but then congrats, Control Priests already beat aggro decks pretty easily. So really, the only situation that is good is against other longer decks, but if those longer decks had you had 6 health they likely have some massive board you also have to deal with and you can’t because you just spent 4+ mana…now you only have 6 left.
The problem is that those other late game decks are all massively mana cheating, something Priest isn’t doing.
This Priest card is just going to help Priest to continue doing what it’s doing: Being bad at late game but now instead of dying on turn 20 you die on turn 24 or something.
The card is decent, don’t get me wrong, but it really does nothing net positive for Priest in the end other than maybe beating decks it was already favored to beat.
I wasn’t aware others knew about it.
In that case, if I have to pick a card I think people aren’t aware of, I’m picking:

I’m really liking this card in brawls. You can put it on your Starship or on some crazy DR minion for cheap.
Giving a minion taunt AND lifesteal for 1 mana is really, really good and I think people are overlooking it. It’s an aggro killer, and it also combos really well in late game when you drop a big deathrattle minion or even something as simple as Gnomelia…1 mana she can have reborn and lifesteal. Pretty nuts in control.