You are right, they can't fly. They offset that by rapid regeneration, near invincibility, driving people mad with a look, longevity, and being the literal blood of Rhysol. Druvin ftw. Hail Rhysol! God of Gods!
EDIT: Oh! And they have sexy white eyes.
EDIT 2: Actually, speaking of Rhysol I should really do some more faith threads. I'm up for another possible mark in a season or two.