Damn it. He holds his breath reflexively, recoils at the first hint of heat, which isn't comfortable for him in general anymore. Heat is hell. He instinctively smacks one hand over his mouth to further avoid breathing in the gas, other hand directed out toward the remaining canisters. Ice crackles over them, blocking the flow of gas.

And because the whole move is reflex on his part, the release of power isn't quite wholly controlled; the temperature in the hallway dips noticeably, some of the gas shifting into frost.