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.

Throwing holy water at demons should be buffed way over its current 2d6 damage, because it’s a fun interaction. Instead, it should severely weaken them, cancel them, stun them, and/or do a large amount of damage (perhaps 50% or some proportion of their max HP, possibly exempted for demon lords whose fights it would trivialize).

In variants where the spell of cure sickness can be cast directionally, casting it at Pestilence has some detrimental effect on him, probably hitting his HP and possibly stunning or even cancelling him.

Stun grenades, which work similarly to regular grenades except they explode for zero or a token amount of damage, and inflict stunning and other types of status effects on things in the blast radius. For instance, there could be a flashbang grenade which stuns and blinds its targets.

Add a potion of milk, working along the same lines as milk in Minecraft, which cancels potion effects (or since not many potions have lasting effects that you’d want to cancel, it cancels various temporary good and bad status effects in general, like confusion, stunning, and invisibility, but not nausea since drinking milk usually makes nausea worse in real life.

You can apply an equipped small shield (or possibly other types of shields) to attack a monster with a shield bash. This could be treated either like a blunt weapon attack, or more likely as a special effect which has a chance of stunning the target. Stunning odds could be higher for either more martial-based roles, or could use a shield skill and scale with that.

If you get hit by a cursed rock from a falling rock trap, you may become stunned for a few turns.

Artifact whistle Nightingale, based on the Nightingale Robber from Russian folklore. When blown, it causes various effects to monsters in a sizeable radius: stunning, confusion, scaring, possibly even instadeath if they are weak monsters or have low HP (or just HP damage). Any of those effects can also happen to the player. The player is guaranteed to become deaf for several dozen turns from blowing the whistle.

As a limiting factor, it will only cause these effects if blown when its invoke timer is ready, and blowing it will internally set its invoke timer as if you invoked it. If blown when its invoke timer is not ready, it will just behave like a regular whistle (and no “ignoring you” message will be shown).

All the various fruits and vegetables have slightly different (and generally good) non-nutritional effects, like with carrots and blindness. Ideas:

• Apples exercise Consitution (and make nurses flee?).
• Pears heal d3 hit points.
• Oranges restore one lost ability point.
• Bananas cure stunning.

In the absence of monster hallucination being implemented, make a monster stunned whenever it would become hallucinating.

Whirly engulfing monsters have a random chance of causing dizziness (stunning) every turn you are engulfed.

Sustain ability also gives stun and confusion resistance, and prevents you from studying books.

Ogresmasher doesn’t need bonuses versus ogres, or confer beneficial properties. It is simply an oversized sledgehammer with such terrible crushing power that it splatters anything it’s swung at. On top of modest damage bonuses, it has chances to instakill sufficiently small monsters, and may inflict negative status effects on large monsters like stunning or slowness (or bleeding, if that is implemented). Probably better if war hammers are made into two-handed weapons.

When trying to descend stairs while stunned, and possibly confused with some probability, you fall down the stairs.

Add some effect to Snickersnee so that it’s not just a slightly better katana. Ideas include confusion resistance, stunning resistance, displacement.