After an hour or two of messing with the game, with a help from an online engine, I can confidently say that the A.I is dogshit and actually needs the spells to stay on par, by cheating basically. But it also does dumb shit like freezing and blocking a same inactive piece at the bumfuck nowhere on the board giving you 2 free turns. Also it seems to get strangely passive when its ahead in material or position and randomly start sacking pieces with a belligerent attack. I guess you need some comeback mechanic?
Unless you really enjoy erotic chess, I'd recommend just taking that gallery unlock at the first story game. But if somehow you don't wanna do that for whatever reason, you can just start a story game and resign immediately, which will unlock a single animation and you can spam it. In addition, the game suffers from terrible and unintuitive camera controls, bad performance optimization, and the A.I can casually make an illegal move by using a spell that takes up their turn while under a check, which allows you to take the king and win. Which is weird since on a semi-normal match of this game, you can't take the king because the game ends by a Checkmate.