@BloodySorcerer
his potential to magic is extremely similar to hers, but he doesn't consider it as such because his talents lie in some kinds of magic he wasn't interested in learning. I wonder why he keeps putting himself down when he is actually really talented.
Comparing only raw spell school potential Milly has him slightly beat (465 vs 434 caps added up) but Zeff still exceeds her in green and spirit. Zeff actually exceeds his old master in all schools except for void which she has 6(!) more potential in with a total point cap of 392, I don't understand why Zeff looks up to his old master so much whilst also obsessing over power caps.
But what really makes Zeff OP is his innate space-time magic (which is similar to Claude's magic immunity and can't be taught?).
Honestly it's just boring to see him put himself down all the time, feels like an attempt by the mangaka to make him appear more humble but to me he just looks dumb and insecure.