New Priest Minion - Lightmaw Netherdrake

Might be better than Duskbreaker. Priest no longer has issues with drawing cards as much as they used to, I doubt it's going to be hard to have both spells in your hand by turn 4...and even if you don't, there's still some redundancy with Xyrella and Hysteria so you're not exactly relying on this alone for boardclears.

They're gonna make Quest Priest into a real thing and we're all gonna hate it...

I don't know if this is good immediately. Hysteria seems more consistent and flexible. It might be good enough to see play, but I'm not hopeful.

However, on rotation this should be pretty strong. Priest is lacking in midrange board clears right now, and Quest Priest has so much search and card generation. I think it's unlikely that this card will be stranded.

Its not that great to be honest. Dealing 3 for 4 mana is no longer as powerful as it used to be, even with that 4/4 body. Also, this card is infinitely less consistent than Duskbreaker, the real reason why it was broken in the first place.

Priest AoE often have to work on demand, because they rarely play for tempo on board. And it would be cruel irony to have one but not the other spell condition this card requires. I have a feeling that would happen really more often than not.

I will concede its a decent card in quest priest, because you can drop it with or without the AoE effect just to get past tier 1 of the quest, something you can't necessarily do with the much better AoE Hysteria. Pretty much everywhere else its just not going to cut it.

Duskbreaker that needs 2 spell types to work. Well Duskbreaker was one of the best board clears in the game when it was last in standard and is still a must-include in dragon priest decks in wild even though those are very rare. We did get Spirit Guide, so getting those spells in quite easy. Not only that, but the shadow and holy spells are pretty good. Lightmaw Netherdrake to me seems like a really good option for control priests, as they often have to "tempo out" Xyrella in order to clear the board early on. This seems like a solid card against aggro, and priest needed another early clear that is not Xyrella or the very situation dependand Hysteria. (Sometimes Hysteria is really bad, especially against token/aggro decks with lots of smaller minions.) However 3 damage might not be good enough those days.

Oh and Hysteria rotates next expansion, so that will only solidify Lightmaw Netherdrakes position as one of priests best control tools.

Standard: Will see play in Quest priest, that deck runs plenty of shadow and holy spells and needs more control tools. However to me the most interesting thing will be Deathrattle control decks. Those often run Vanndar Stormpike, and it will be interesting to see if those decks will abandon Vanndar Stormpike and include cards like Lightmaw Netherdrake and Xyrella again. 

Wild: This might see play/experimentation in reno priest decks i guess? It certainly wont see play in Big/ress priest decks. Dragon priest might also experiment with it.

Probably at least decent in a Priest deck that runs lots of Holy and Shadow spells.

Even if you're running Shadow Priest, because there are so many ways to get a Holy spell into your hand, especially if you happen to be playing again another Priest (Thief Priest here we go), this is still a viable option 

This one is at least decent enough to see play - some sort of Dragon Priest will emerge in Standard :) :) - at least i hope it will.