Remove or greatly reduce the chance of monsters to get a wand of teleportation, on the basis that the vast majority of the zaps that monsters are given with these wands end up in the player’s hands, allowing them to bring a pile of them to the Astral Plane and use them to make that level significantly easier. If they do not generate in monster inventories, a full game might see about 3 or 4 wands appear on average.

Replace the wand of teleportation with a potion of teleportation (leave the ring and scroll, and possibly the spell of teleport away, as-is). You could still teleport monsters, but possibly not objects any more, by throwing the potion of teleportation which would then randomly teleport everything that it gets on or which breathes its vapors.

This also is intended to make the Astral Plane more difficult by removing easy zaps and snaps of the wand, making it a much more limited resource.

Occasionally when a monster decides to use a teleportation wand as a defensive item, and the level is not non-teleport, it decides to zap you instead of itself.

Breaking a wand of teleportation will teleport as many monsters around you as there are charges left in the wand, always including yourself.

Monsters can defensively zap you with a wand of teleportation if you are not on a non-teleport level.