I like instant-speed Lava Axes for creatures, and that's basically what this is. Toss this in front of an unblocked creature and you'll probably end up trading with it. That said though, this does only produce a 5/5 wall for one turn, so unless you're being swung at, this won't be of much use to you.
Pros: Instant-speed blocker for 3
Cons: Only makes a wall, must sack at end of turn