The Iron Helm of Dor-Lomin [5,+20]
+4 strength, dexterity, constitution. Provides resistance to acid, lightning, fire, cold, fear. Cannot be harmed by acid, electricity, fire, cold. Grants telepathy. Grants the ability to see invisible things.
Radius 1 light.
Min Level 40, Max Level 127, Generation chance 5, 7.5 lbs

(Angband 3.1.2v2)