# Non-teleport level
"A mysterious force prevents you from teleporting!"
A non-teleport level is any level that prevents all forms of self-teleportation within the same level, whether from the scroll of teleportation, teleportitis, or any other such method. There are generally no restrictions on level teleporting or branchporting with the Eye of the Aethiopica. However, you cannot levelport from Sokoban, or in the quest without your quest leader's permission. And you cannot leave the End Game in any other way than the portals.
On a non-teleport level, you will not be able to escape the monsters by teleporting yourself, but neither will the monsters escape from you. Thus you might need to change from your usual strategy.
Even in 3.4.3, monsters have to learn teleport restrictions through personal experience. Monsters frequently waste one scroll of teleportation trying to escape you. Nymphs, nurses and foocubi will still try to teleport away from you, but will always fail. Once an individual monster has attempted teleportation by such methods, or stepped on a teleport trap, on a non-teleport level, it does not do so again.[1][2][3] Such a wised-up monster will also try not to wander onto any teleport trap (except to escape),[4] and has a 75% chance of escaping traps it walks onto.[5]
On non-teleport levels, you can still teleport monsters and items; the only restrictions on teleporting are that creatures (including the player) cannot teleport themselves, and the quantum mechanic's teleport attack does not work. Therefore, a wand of teleportation is an incredibly effective defense in high-density levels such as Moloch's Sanctum and the Astral Plane.
Covetous monsters will still be able to warp to the up-staircase. Covetous monsters include master and arch-liches, Quest nemeses, and named demons. Many levels where master liches tend to appear, such as demon lairs, are non-teleport. If you have telepathy, you can easily see where such monsters are warping. However, even if you have teleport control, you will not be able to follow them by teleporting. You will have to walk to the up staircase and endure injury while the monster warps and heals. Once you can reach the up staircase, stand on it to block it. This tactic does not work on the Astral Plane—covetous monsters will simply teleport to retreat a few spaces.
If you are engulfed on a non-teleport level, you cannot escape by teleporting yourself; however, if you teleport the engulfing monster, you will stay put and the monster will be teleported away. This is in contrast to regular levels, where you go with the engulfing monster.

List of non-teleport levels
All of Sokoban
The Quest home level
The Rogue and Samurai Quest goal levels
Fort Ludios
Medusa's Island
The Castle
The Valley of the Dead
Demon lairs (Asmodeus, Baalzebub, Juiblex, and Orcus)
All of Vlad's Tower
The Gehennom levels with wizard towers
Moloch's Sanctum
The Endgame

The following information pertains to an upcoming version (NetHack 3.7.0). If this version is now released, please verify that it is still accurate, then update the page to incorporate this information.

Demon lairs are no longer non-teleport, but demon lords and princes suppress the teleportation of you or any monster that isn't a demon lord or prince, in Gehennom.
SLASH'EM
In addition, the following SLASH'EM levels are also no-teleport:

Grund's Stronghold
The Lawful Quest
The black market
The Yeoman quest nemesis level
The additional demon lairs (Yeenoghu, Geryon, Dispater, and Demogorgon)
However, teleportation is allowed in the Valley of the Dead.

This page may need to be updated for the current version of NetHack.
It may contain text specific to NetHack 3.4.3. Information on this page may be out of date.
Editors: After reviewing this page and making necessary edits, please change the {{nethack-343}} tag to the current version's tag or {{noversion}} as appropriate.

References

↑ muse.c in NetHack 3.4.3, line 457

↑ muse.c in NetHack 3.4.3, line 583

↑ trap.c in NetHack 3.4.3, line 1171

↑ mon.c in NetHack 3.4.3, line 1188

↑ trap.c in NetHack 3.4.3, line 1706