Ring of teleportation
|Base price||200 zm|
|Probability out of rings||3.57%|
|Probability out of items in:|
Wearing a ring of teleportation gives you teleportitis. These rings are often generated cursed. A cursed, price 200 ring is very likely teleportation. To be sure, you can uncurse it and put it on - if ctrl + t gives "You cannot teleport at will" instead of "You don't know that spell", it is teleportation.
The usefulness of teleportitis is rather schizophrenic; uncontrolled, it is usually considered a great annoyance, as you will often be teleported into danger (or worse, out of shops). Once the player gains teleport control, it is a great boon, and when combined with magic mapping, allows you to clear levels of Gehennom in seconds.
The usefulness of this ring depends on whether or not you have teleport control, and how. If you don't have it, it is mostly useless below XL 12 (8 for wizards). After that point, it can be useful as a swappable escape item, but a wand or scroll of teleportation is probably preferable. If you have teleport control from a ring, whether or not to use this ring is a choice: if you choose to eat a corpse which conveys teleportitis, it spares you the ring slot if you want controlled teleports. However, you must always keep your ring of teleport control on, and if you lose it somehow, you are stuck with uncontrolled teleportitis. If you have teleport control intrinsically or from the Master Key of Thievery, you should pretty much always eat a corpse that conveys teleportitis instead of wearing a ring of teleportation. If you're using the Key, bag it when the Wizard appears.
Even without any teleport control source, the ring is a controllable source of teleportitis, and thus can be used for niche situations like escaping from vaults.
In UnNetHack, dropping this ring down a sink will teleport the sink to a random location.