How did Xykon survive his fight...

[hamishspence]

And mind you, his level his debatable, even though I really dont see him being under 25 but you wont make me believe that a guy who spent 8 hours each day crafting magic items, got a ring to make him immune to fire and always have overland flight cast on him didnt have quite a few buffs and protective items.

He got an item of fire immunity (if his hint here is honest- but we never actually see it so we don't know what it is.

While "Ring of Energy Immunity" (an epic ring) is a fairly reasonable surmise, it would put his level way up, due to the restrictions of the Forge Ring feat:

Forge Epic Ring [Item Creation][Epic]
Prerequisites
Forge Ring, Knowledge (arcana) 35 ranks, Spellcraft 35 ranks.

Benefit
You can forge magic rings that exceed the normal limits for such items.

which would put him at level 32 minimum.