[He sighs, keeping his gaze pointed straight ahead this time.]

I'll do what's necessary to keep the earth protected from threats such as these; but bloodshed begets more bloodshed, and it's best to try to break the cycle if at all possible.

[He stops at a door, waves a hand, and it opens. It looks like a guest room, but he's not here to show her where she's going to be... staying. He doesn't even think she really requires a spot in the Sanctum.]

I'd prefer to avoid killing the Master if need be; containing them, imprisoning them, or otherwise debilitating them would be preferable to that.