Blast Wave is a 5 Mana Cost Epic Mage Spell card from the Rastakhan's Rumble set!
Deal 2 damage to all minions. Overkill: Add a random Mage spell to your hand.
If you’re burning and you know it, wave your hands!
Blast Wave Card Review
Important note, if someone doesn’t realize it yet, Overkill on AoE triggers for every minion Overkilled, not just once. So if you use this on a board full of 1/1’s, you get A LOT of cards.
However, if we look at the card by itself, with no extra synergies, it’s really weak. Paying 5 mana for 2 AoE damage is a lot – the same costed 3 mana (Volcanic Potion) and it wasn’t even that widespread. The card is meant to make up with the Overkill effect, but triggering it is not that easy. At the base level, it will trigger ONLY on 1 health minions, and people rarely have a full board of 1 health minions. Then, if they only have 1-2 of them, you don’t really need an AoE most of the time, just pinging them is fine. Right now the only decks this would work well against are Even & Odd Paladin, especially the latter.
The card becomes more interesting if you add some Spell Damage to it, Celestial Emissary in particular. Those two deal 4 AoE damage for 7 mana, guaranteeing at least 1 random spell (from killing the Emissary himself) and then giving extra ones for every 3 or less health minion (while killing everything up to 4 health). That actually sounds good – it wouldn’t be hard to get A LOT of value from this combo. The main problem is that it’s a 2 cards combo, and 2 card combos are always harder to justify than just a single removal spell.
I think that right now slow Mage decks have access to enough AoE and they don’t need a lot of value generation, because Frost Lich Jaina is enough (and they still have stuff like The Lich King or Sindragosa). However, this could be interesting after the rotation – Dragon's Fury will be gone, a lot of value tools will be gone, so it might come handy.
Right now I could see Quest Mage trying it out – it’s AoE + you generate extra spells for the sake of Quest. Is Quest Mage good enough, though? I think it might see some niche, off-meta play.
Card rating: 4/10 right now (because Mage has abundance of AoE and late game value), but should get much better after the rotation