[ano]

In most cases Djinn will beat an opponent even with trample. There're a few SC's that are able to hit through his 35 Defence (acquired easily). Also, Djinn will inevitably appear in HoF (maybe even after his very first battle because trampling produces much XP) and then (attention!) you may reforge the lamp and then get him back with Ritual of Rebirth. It is probably a bug that he is not unique...
To make Djinn tremendously effective you need:
Vine Shield
Another good shield with high parry
Starshine skullcap (optional, to have more MR)
Ring of Regeneration
Pendant of Luck

Even with 2 shields he will still have fist attack which is not bad considering his parameters even against size 6 enemies (which you don't want to meet of course). Probably, it is Djinn's feature.

Script:
Iron will
Invul
Earthpower
Mistform
Mirror Image

You just don't have place in script to cast luck so you have to use an item. But it may be replaced with Stone Bird for even better parameters if you find place for Luck in your script.
Djinn is awesome and quite hard to kill.