Hmm maybe. How about this

Cazador vs Thay. Cazador either wants in to take over or they keep getting in each others way. Maybe the werewolfs are kept as slave and they want revenge against all undead. Enter: Hela werewolf gnome bard. Renagade that inspires an uprising. Lol

Or how about Cazador lost already to a high thay lich and bound Cazador to Baldur's Gate or something in the city as punishment and Astarion is going to take his place as the bound victim using devil magic or a deal to bypass the spell. Cazador goes free kills and thralls the rest of the city and launches a full scale assault against Thay empire.

Damn Larian needs to release a patch. I'm fanfic'ing now. Lol