I've used Tara a few times to good effect doing something similar. On top of Void Wretches, Canine Remains make excellent scheme runners. Crooligans and Necropunks are also supposed to be, but I haven't personally had a chance to use them yet. Rotten Belles are amazing models, and have so many uses it's silly. Chiaki (sp?) the Niece is an amazing support piece as well. Finally, if you are going to use Karina's summoning (I'd consider it) you'll want several horrors, such as Punk Zombies, Drowned, Guild Autopsies, and the various students. The Valedictorian is another big beater to consider and comes with the other students. If you are going Mercs, Bishop is also a good bomb, as he has 3 ap to start, and with fast can be pretty nuts. I've not had much luck with Bete Noir personally, but I also haven't used her a ton.