Giant, huh? The ancient foes of Brandon's own land and family, the Fomorians, were giants as well, so he'd been taught a decent amount about that breed of Titanspawn.
"Does Mog feed you and the others his blood? Did he have your permission to change you like this? And what will happen to you if he perishes?" However, Brand didn't know what exactly thralldom entailed. If Mog was going around corrupting mortals against their will, Brand might be obligated to end him.