3 mana 3/5 was good when it required the enemy to have 3 enemies. 3 mana 3/5 only on your opponnents turn will potentially be even better especially with that elemental tag... which will do something. Really hard to think about all the upsides and downsides when a giant part of the card with it's tag is basically unknown.
Imo it could be good in highlander decks. it's essentially just your on turn 3 taunt next to second hand. More taunts = better highlander decks. Priest highlander will probably still be viable if they use this as anti aggression to get to their 12 heal
You can run this in an aggro decks too guys... you can buff it easily on your turn if you play zoo warlock for example. And it will protect all your small minions on your turn since its a 3/5 taunt for 3 mana.