Wielding Tempest, in addition to its existing effects, protects you from being paralyzed by lightning on the Plane of Air. Also, when its area-of-effect lightning effect triggers, fog clouds and gas clouds around the center of the effect are destroyed or blown away, “clearing the air”.

Convert the sleeping gas trap to just “gas trap”, and make it scale based on the difficulty. Each individual trap releases a single type of gas; which type is partially dependent on the level difficulty. At low levels, they all emit sleeping gas like normal. At higher levels, they emit stunning hallucination gas like container traps, clouds of poison gas, and maybe even nastier gases that reduce speed or miasmas that cause illness.

Allow for gas clouds of different types (confusion gas, sleep gas, hallucination gas, etc) by passing an additional argument to create_gas_cloud.

Clouds of sleep gas would immediately have a use in Nazgul and orange dragon breath attacks, which are already described as such. They might also be useful for sleeping gas traps, which would emit an actual cloud of sleep gas. Depending on implementation, the sleep gas cloud could have only a chance of inducing sleep rather than always knocking you out, which could make it tactically interesting to navigate/teleport/etc rather than just getting put to sleep and having the cloud gone by the time you wake up.

Strangulation protects you from drowning, since you cannot inhale water if you can’t inhale at all. It also prevents potion vapor inhalation effects and the inhalation effects of gas clouds. Basically it works like magical breathing except you die in 6 turns.

Random tins can contain beans as their contents, which make you emit a stinking cloud when or after eating them.

Cursed boots that you have worn for at least 300 turns should emit a stinking cloud when finally removed.

Add an additional container trap effect which creates a stinking cloud centered on the container. If the player caused the cloud to be created, they are counted as responsible for anything killed by the cloud.

Breaking a wand of wind creates a stinking cloud centered on its space, because it’s “breaking wind”. Possibly only when cursed.

Noxious sphere, a sphere similar to its siblings in that it has an active explosion attack, but the explosion is of poison and creates a 3x3 (or larger) stinking cloud centered on the sphere.

Chlorate candles, which appear rarely. They provide immunity to stinking clouds when carried, and stay lit when the hero is engulfed.

When a monster and a gas cloud are on the same space, and you are adjacent to that space and non-blind, the game should render the monster rather than the cloud.

When a pool of raw sewage boils away, it creates a poison gas cloud over that space.

Stinking clouds spread out from their origin point instead of using a preset diagonal shape.

Thrown potions of sickness create a stinking cloud centered on the spot they break. If the potion were diluted, the cloud is either smaller or disperses faster.

When an egg gets very, very old, it cracks and releases a small stinking cloud. If it happens to be carried by the player, the cloud centers on the player. When it is close to rotten, the player can throw it and it will release the stinking cloud wherever it shatters. (The chance of it releasing a stinking cloud increases with age, asymptotically towards 100% the older the egg is).

Attempting to eat an old rotten egg will create the stinking cloud on the player’s square.

More harassment effects: the chance of respawning the Wizard is a fixed 1/7 and the rest of the effects are equal probability. Multiple non-duplicate effects may happen at the same time.

• Unchanged: curse items, summon nasties, vaguely nervous, aggravate monsters
• Darken much of the level, and extinguish, destroy, or cut the remaining lifetime of light sources. Maybe also blind the player.
• Drop boulders around the upstairs, or iron bars.
• Spawn pools centered on the player, with sea monsters in them.
• Spawn lava around the level, not under the player.
• Create a hole or pit under the player.
• Create a stinking cloud centered on the player.
• If you are carrying the Amulet, it teleports to a random square on your level or the level below.
• If you are carrying the Amulet, it (and possibly any fake Amulets) becomes heavier. This either lasts until the next harassment triggers, or is permanent but the total amount of weight added to the amulet has some sort of cap on it. This is interesting primarily because it targets carry cap, which is a valuable end-game resource.
• A variety of powerful player debuffs such as dealing half damage, taking double damage, blocking HP or Pw regeneration, super hunger, etc.

Dungeon branch or level filled with toxic contact gas (breathless doesn’t help, or only helps a little) so that you constantly take damage and must bring a lot of healing with you. The deeper you go, the worse the gas becomes, but the loot gets better.

Remove the scroll of stinking cloud in favor of a potion that when shattered releases a stinking cloud. Drinking this makes you vomit or become ill.