Most of these Critical Threats from Dungeon Magazine, I find rather boring. Not this one. Homnar Thest would fit right in around Ptolus.
Master Thest as some call him is a weretoad, and a nasty one. He runs a smuggling and kidnapping operation with some fellow weretoads. He sells victims into slavery. Sounds like he could be part of any number of groups in the city. He would work well with the Ennin.
There's no adventure attached to the NPC villain, but the personality and nature of this beastly fellow almost writes one for you.
On the surface he comes off as a prosperous merchant. He's very portly, yet agile. He wears expensive cloths, jewelry, etc. He's a glutton and greedy to boot. Oh, and he eats people when he can get away with it.
In Giant Toad form he can swallow targets whole. If he catches a character alone things could go very badly, or result in a kidnapping. Have a player you know will be missing a couple of sessions? This could be a reason their character isn't around, and the ransom might be expensive.