Div-e Sepid

The chieftain of the divs of Mazandaran, white as chalk and enormous, and he took an entire army by taking their eyes. The king and every paladin with him went blind in a single night and were put in a hole in the ground, and the cure was not a prayer or a herb or a healer. The cure was him. Somebody had to go into the cave, kill him, and come back out carrying the part of him that would undo it.

Take the Sight: 40 ft, save Wis Mind, fail save roll 3d8+6 and the target is blinded, permanently, by nothing that any healer will be able to find or treat. Cooldown 3 rounds. He opens with this and he uses it on the most capable creature present. Great Fists: bludgeoning, melee 15 ft, +6 to hit, 3d8+6, twice each round, and he does not need to see well to do it.

The Cure Is Inside Him: blindness he has inflicted is lifted by nothing except his own liver - or in some tellings his heart and blood - taken from the body after he is dead and used on the eyes. No spell, no cleric, no rest and no time will do it. A party that flees a losing fight has permanently blinded companions and one way to fix it, which is to go back. Of the Dark Cave: he fights in his own lightless hall, where blindness costs him nothing at all and costs the party everything.