Hearthpwn

might see play in my undead barnabus deck :D hopefully it will work well,cant wait to play it :D

Pretty strong setup after a board clear and your opponent is a zoo deck.

The only use for this card is to topdeck it in arena

This seems awful. Let's say you proc it for free with something like the DK location, and you use this at like 9 mana (which is A LOT), then you're paying all of that mana for one 4/5 and five 2/2. That's like a best case and it's absolutely horrible.

A card created specifically for the DK Location.

This card has to survive until the following turn to be powerful, which means it's awful.

So if the enemy hits this, do we spend all of the mana next turn?

That was my exact first question as well.

I doubt it, because it's not an overload or destroy mana crystal effect. It would spend your unused mana crystals during your opponent's turn and then your mana crystals would refresh like normal at the start of your turn.

I'm going to assume it spends the mana you had left over.  Which is mildly interesting, but probably extremely weak.

mana doesn't reset until the start of turn