I used a Spriggen Assassin again and I think I'm near the bottom of the Dungeon...
He went Super Saiyan when he had acquired the ability to cast spells. That allowed me to learn Slow which is sick when mixed with the Venom sword I currently have (stick and move). They'll be slow as hell, poisoned and I can kite them around an open area or tunnel. This doesn't work too well with groups obviously but its fantastic for the big monsters.
I'm still weak against large groups and the undead. If I had the Book of Necromancy I would be able to learn Dispel Undead which would take care of the latter issue. With large groups I have to use the "fall back to a tunnel" method. The stair method is too unreliable (in regards to taking up enemies you may not want).
I also think I'm a little under leveled for the area I'm currently at

(Level 13). I saved and quit though, I've been playing this run for a good while and I know I'm going to do something stupid, I'll tackle it later.