Remove the ability of unicorn horns to cure hallucination, as otherwise it’s a trivial status effect to fix once you have one.

Unicorn horn skill should factor into, or even be the primary factor in, whether using a unicorn horn cures you of an affliction.

Because it’s a status effect with some downsides, make unicorn horns cure invisibility by removing it. Maybe temporary speed too.

If you polymorph uncontrolled while wielding a unicorn horn, you may become a unicorn corresponding to your alignment.

When a cursed unicorn horn makes you nauseous and about to start vomiting, print a message “You feel nauseous.”

Dipping a unicorn horn in acid dissolves and destroys the horn, producing a potion of healing.

Unicorn horns become less effective the more you consort with foocubi, as you are becoming less pure.

Dipping a unicorn horn into a potion of a type it normally “cures” will do nothing if the potion is cursed.

Every unicorn horn cures one type of ailment and no others.

Unicorn horns are a one-handed weapon that does 1d3 damage, and train no skill (the skill is removed outright). However, when wielding one without gloves, you automatically “apply” it (not consuming any turns the same way as a stethoscope), every turn.

Hitting monsters with a non-cursed unicorn horn cures them of status afflictions. Hitting them with a cursed horn gives them status afflictions.

If a peaceful unicorn sees you wielding or applying a unicorn horn, it gets angry.

In an effort to make unicorn horns not infinitely usable but also preserve their other good qualities: Split the unicorn horn into two items, the horn, a simple tool which now has a number of charges, and a “unicorn spear” / “hardened unicorn horn” which is a weapon.

Both items have the same base damage, are two-handed, and use the unicorn horn skill, but reading a scroll of enchant weapon while wielding a unicorn horn will transform it into the weapon version like how crysknives work. The weapon cannot be used to cure ailments.

Every time you use a unicorn horn to cure a problem, the chances of any unicorn horn curing that problem in the future slightly and permanently decrease. Effectively building up an immunity to the effects of unicorn horns.

A conduct that is broken if you use a unicorn horn. (Possibly, only if you get healing effects from a unicorn horn; using it as a weapon is fine.)

Dipping cursed unicorn horns into harmless potions turns them into harmful potions.

Healers can use an uncursed unicorn horn as if it’s blessed. They could also get the unicorn applied passively every turn as long as it’s wielded (with or without gloves on).

Give unicorn horns a to-hit penalty: they are not a manufactured weapon, and are not designed to be wielded in your hand.

Cancelling a unicorn horn makes it non-magical and removes its curative properties.

Unicorn horn skill is also trained by curing things with it, and its chance of fixing something increases with skill level.

Unicorn horns no longer cure afflictions completely; they will only reduce the duration of one.