Ring of resist corrosion
An amulet of resist corrosion grants its wearer corrosion resistance, providing a 50% chance of negating each level of the corrosion status effect you would normally receive. It also reduces the amount of acid damage you suffer by 50%, further reducing the odds of any given attack corroding you.
Desirability
When facing acid damage, corrosion resistance is very helpful, keeping the damage you take down and preventing corrosion from rendering you weak and fragile. Acid damage is a serious threat all throughout the Slime Pits, and can also be an issue when dealing with caustic shrikes, tengu reavers, yellow draconians, liches, and oklob plants. Outside of those circumstances, however, the amulet is utterly worthless for regular wear.
History
Prior to the corrosion overhaul of 0.15, corrosion resistance offered a 90% chance of negating corrosion effects against vulnerable weapons and armour. This stacked with other sources of resistance.