Automatic Brassblaster

Defender
{x}: Automatic Brassblaster gets +X/+0 until end of turn. Spend only steam-powered mana on X.
Crew 1 (Tap any number of untapped creatures you control with total power 1 or greater: This permanent becomes an artifact creature until end of turn.)
"Dangit, I'm all out of ammunition. Now what can I do with these empty brass cartridges..."