ToME WikiSirrocco This just showed up in the Black Market, v2.3.3
The Feathers Cloak 'Gwaros' [1, +10] It provides immunity to acid, electricity and fire. It provides resistance to light, confusion, sound, and disenchantment. It cannot be harmed by acid, cold, lightning or fire.
I even had the money for it. It was entirely too mindboggling. I had to share.
LordEstraven: IIRC, quad-immunity randarts aren't supposed to be generated.
Sirrocco: It wasn't quad. It was only triple (no cold). It's still pretty freakishly impressive - especially for a lv 30-some-odd geomancer.
LordEstraven: Ah, my bad. Part of me still objects to randarts with more than one immunity though.
FedericoOdorizzi: There was a similar discussione somewhere in this wiki one year ago I think; some of the items posted there were also really impressive. If I happen to fine that page again I'll link it 
Here it is: Best Random Artifacts! There were also a quad-immunity armour and a quad-immunity cloak!