iWear's "Secret" Hideout

The intruder still looks like a black smear on the bunker wall. He could slither up to the top and look for the hatch, or he could go somewhere else. Until the drone enters the building proper, it won't see him, and he won't see it. But when it does, he'll quickly pounce on it, possibly before it gets a good view of him. His smokelike form will fall upon the drone and attempt to dismantle it the way it did the explosives. Depending on what sort of sensors it uses, it might be able to get a good read on what he is while he does it.