This is just a sweet card. I was skeptical of elemental with the first couple elemental synergies they've revealed. But man. With this and the shaman legendary? Elementals might be the savior the meta needs.
Priest and mage already have good ways to play this early. Mage has the 2 mana 2 damage spell, and priest has the mini-shifting shade, plus you can run tar creeper for the nuts curve. One or two more cards this good and I could see putting that 1 mana 1/2 thing into your deck.
Really powerful with an elemental, hot garbage without. Whether it'll see play will depend a lot on if there are good 5 mana cards that require an elemental. Mage for example has Water Elemental on 4, also a good alternative.
I see myself inevitably trying to construct a sub-optimal off-meta midrange elemental paladin deck, casting aside the unplayable garbage paladin itself is getting (for any purposes other than aggro), only to realize shaman is just better in every way :p
P.D.: This has so many uses. It could even help a control rogue rise finally. Blizzard always gave rogue strong late game cards without any anti-aggro stuff to make them reach late game. This and some of the other elemental buddies might give it that final push that always left it away from meta.
People are not look past having the perfect curve AND hand.
This card will be trash tier most of the time as the most optimal time to play it would be turn 4 after an elemental is played. THAT IS A HUGE REQUIREMENT TO GET ITS EFFECT.
So far, there's at least 2 elementals that can be used in an elemental control deck that could be used in turn 3: Tar Creeper/card] (the most obvious curve) and [card]Fire Fly (since it fuels your hand with another elemental to activate even more "last turn"s effects).
If there's at least another card worth playing on turn 3, I'd say that this card will never be considered trash tier for it's consistency on activating the battlecry.