Frankly, there's no limit on how long Galahad can do this. He knows how to be still and silent, and he knows his own feelings of leaving his body, of hovering above it like a ghost. He feels Magnus' touch, but it's distant and unreal. He is a corpse, fallen beneath the claws of a dragon. He no longer needs to breathe or feel, only to watch while Sunny clambers over them.