Hearthpwn

In an heavy Aggro meta its a good card: 6 health Taunt at turn 4 can really slow them down. In addition it has Deathrattle, so it counts for quest synergy. Not OP or anything but at last playble in a dedicated Deathrattle deck (that seems to be the direction in which they want to push Priest control deck for what we've seen so far in Un'goro), but probably not so good in any other scenario.

It also kind replace Twilight Guardian now that it's going to go out from Standard.

A 1 mana drop that also give some istant value! And also with Deathrattle! Finally something in addition to Northshire Cleric, now that Twilight Whelp is going out of Standard.

I don't really know if comparing this with Mind Vision it's right: Vision copy cards only from your opponent HAND, while this little guy can take something from his DECK. Ofc it's heavely RNG based but at last this is a creature and with the nerf to Small-Time Buccaneer's healt and the costant Patches the Pirate I belive it's a good thing.

I don't know how this card can be good for otk, but for a Reno-style/control deck it'll be probably a must: semi-tutor card to search for "THAT removal" it seems quite strong. Also in Priests drawing has always been an issue and this card creates anyway some value with a low cost card (and Priest deck don't have many 2 mana cards at this point anyway, since Wyrmrest Agent is going out of Standard).

Also in decks with few spells the search will be in a very restricted range of cards so it's effect can be maximized.

Maybe with this card, would Priests be able to still play the "one-card-copy" deck? A N'zoth/Kazakus control deck?

Amara, Warden of Hope could easly be the new Reno and for what we've seen of Un'goro till now, it seems that the meta will slow down a bit with lots of low cost Taunt minions.

I belive that we've seen few Elementals cards in order to say if this new mechanic is good or not but Jade will remain the "late game-killer" in its current state: at some point it's impossibile to counter a costant flood of XX/XX minions and you'll simply get trampled. For what they've show us, Elementals will probably be a good choice versus Aggro and for Midrange deck but nothing on sight about late game. So let's wait and see.

On top of that, Jade and Elementals are completly different mechanics so comparing them is not something that have that much sense... but well, that's Kripp afterall.