It cures your Poisoned state when you click on it while wearing it, you can use it once every 10~ seconds. When you move it to your ring slot, you will receive 200 damage (will be less if wearing equipment), but if you do it while standing in a protection zone you won't take any damage, once you've put it on you don't have to take it off for it to recharge. However, it's advisable to take it off and wear again after using it around 60 times, or it will be depleted for 1 day, when it happens you might get Poisoned or Cursed. If it happens you receive around 15 turns of damage, increasing from 1 until the last damage of 460+ (remove the curse eating a Hydra Tongue Salad or asking for healing in a temple). When it happens, the message about the claw being usable only for levels 100+ disappears and the claw can't be put in ring slot (becomes a decoration object).
When you wear it, it will say "It tightens around your wrist as you take it on." and also "Ouch! The serpent claw stabbed you."