I love djinn, he's the best spellcaster in the game. He has one problem though - if he's fighting anything smaller than size 6, he's just going to try to trample them, which may not be what you wanted.
From a recent game.... not the best I've ever had but a lot of fun:
I had to trim out his slots, this was him essentially naked. His regeneration was 100+ per turn. I kept switching out equipment as necessary. He ended up fighting 2-3 of the doom horrors singlehandedly and winning.