AlienWarlord
Maybe a multiple summon first so you can get more choises? Great sage and predator are just great , great sage is what the mc needs to start developing new and better magic, theres also the possesion that rimuru uses againts the ork , for predator just easy and powerfull stacking of skill , but it loses a lot without great sage control. For new summons fate would give you a lot of choises original sinn/root from deadman wonderland is all rounded option
I think he should buy healing magic/regeneration at least, maybe a second element though i'm not sure how he'd explain that since so far you haven't mentioned the possibility of having dual elements. Next he could perhaps buy a flying broom from Harry Potter so he himself can fly and it might be a happy event to have the girls cling to him when they lift off for the first time. Another favorite of the Harry Potter series would be the 'eat slugs' spell for targeting the fox guy, aside from pretty much being killed socially i doubt many people would be up for continuing to fight when they're suddenly forced to barf slugs.