An enchanted obsidian stone weighing 240g that is the objective of the quest given by [[Senex]].
Finding it at the bottom of the [[Fungal Caves]] and defeating [[Sieni Fusanga]] are only half the battle. The since the stone is in the middle of a small underground lake. If you have gained the [[Swimming]] status from a fountain, this is no problem. Otherwise a [[wand]] or [[ring]] of [[Polymorph]] can easily change you into a flying/ethereal/swimming creature to grab it. Be - but be careful about transforming into a weak creature around strong enemies. The [[belt|belt of levitation]] from defeating Huang Ming Pong will also work, but you can '''instantly drown''' if it is broken or removed.
The stone's magical abilities are not merely stated - it will occasionally "release torrential rain" in an area around you. Being inundated with water shouldn't be any problem unless you or your allies have equipment prone to rusting. It may even be worth carrying around the shard as a portable 'fire extinguisher'!