I initially thought of why this guy doesn't want to use charm magic but can resort to summoning a succubus (also why doesn't he just summon another one? He can send them back anytime). Charm magic is like a cheat code, it's no fun, it's unnatural. But a succubus, after she drains you of ur cum, she's still not in love with you (probably) and you manage to woo her, now that's impressive.