[We'll return to McGillis's cool escape plan in a second and the flaws Izou sees in it, but first;]

M'Yeah. When a heroic spirit gets summoned as a servant, th'mage that summons'em has three command seals as proof've th'contract. If they use one of 'em to issue a command, y'gotta do it no matter what. Like, yer body will just do it.

A servant who refuses t'comply ain't worth shit, so a lotta mages will threaten you with that.