I solo'd Dread Horn!!! Well, I died, and Dread Horn didn't die, but my dragon didn't die either - although it got awful close a few times... However I did get all the keys solo, so my dragon has eaten just about anything that can spawn in the Wealde except paragon cu sidhe (changelings, Spite, Irk, Guile, all the named spiders). I guess I've also killed just about everything that spawns in Bedlam as well, except for the Grizzle himself.
I have however killed Yamandon with a cu sidhe, solo. That was a painful experience though, and not one I'd care to repeat...
Paragon succubus are my testing ground to see how well I am doing with my suit. I've gotten to the place where I can kill them fairly easily solo with a cu sidhe. I've never tried my dragon, but I don't think I ever will because the cu sidhe's damage matches up with the succubus weaknesses much better, and I really want to be able to ride when I am around a paragon succubus. If something goes wrong and they target you, you do
not want to be caught on foot...