Still grinning, Callaghan rubs his hands together briefly to try and generate a bit more warmth before reaching for some of the snow. It chills his fingers, but he's already forming it in to a ball.

Heart? Well, he has it, but he's mostly putting it to use making ammo. For a period of time he's willing to let take care of the throwing- at least, until one goes down beside him. A sympathetic wince, and then he makes a decision, popping his head up briefly before grabbing another snowball, then-

Incoming, Mister Stark!