That seems like a pretty expensive way to deal ~9 damage, and there are a number of ways of shutting down Boltstorm. Getting 2 armor drastically reduces the damage he does on average, Agony completely cripples him, he's really not very tough, and you've invested all of your mana and your first several turns worth of actions in him.
I'd rather try a Sniper rush. The Sniper is only slightly more expensive, but he's much less vulnerable to armor and ways to reduce attack strength, plus he can cover pretty much the whole board instead of needing very precise positioning.
