If you give your pet a scroll, and it is a scroll that monsters can normally read, it reads it on its next turn.

Intelligent monsters will deliberately flash a camera at you to blind you if they come across one.

Shapechanging monsters are cognizant of when they’ve turned into a form that’s much stronger than their usual; if they happen to have an amulet of unchanging, they will wear it when in such a form.

Monsters can zap wands of opening at you, which causes items to randomly fall out of containers you are carrying. (For symmetry, the hero should probably be able to do the same to monsters that are carrying containers.)

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.

Assuming an implementation that lets monsters wear rings and lets you pick and choose what your pet equips: You can have your pets wear an amulet of unchanging to make them immune from being polymorphed or shapeshifting; possibly the rings of sustain ability could protect from both as well, and having them wear protection from shape changers could be used to prevent them from shapeshifting, if they are a shapeshifter.

If a player fear system is implemented: if the player is adjacent to a creature standing on a scroll of scare monster, they will become scared of that creature. Intelligent creatures will deploy a scroll of scare monster to take advantage of this.

Monsters can zap a wand of probing at you, which inflicts the studied debuff on you.

Monsters can now zap cancellation at the player; effects of cancellation on the player include draining Pw (and possibly maximum Pw if Pw hits 0) and removing magical temporary intrinsics such as invisibility, speed, and detect monsters. It does NOT cancel the player’s entire inventory, as this does not happen when the player zaps cancellation at a monster.

Whenever a monster tries to read a scroll of teleportation and level teleports to the current level (“foo shudders for a moment”), you are prompted to call the scroll.

Monsters can drink potions of booze as a defensive item, but only when fleeing. It cancels their fleeing and confuses them.

Monsters can wear amulets of ESP. This allows them to know your exact location (regardless of invisibility or displacement) when you are within the telepathy radius.

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

Some monsters, a subset of item-using monsters, can’t read scrolls even though they can use all other items. Trolls and some orcs would be in this set (possibly even allow some members of a species to read and some not to, based on their internal monster ID.)

Hostile monsters zap wands of make invisible at fellow hostile monsters, allowing monsters that can’t usually use items to become invisible.

Remove the monster spell destroy armor, and instead allow them to read destroy armor scrolls at you offensively.

If you have egg on your face, your Charisma is temporarily and sharply reduced, lasting until either you get hit by or immersed in water or #wipe with a towel. This could also apply to having cream pie on your face.

A possible addition is for monsters to throw random (non-cockatrice) eggs at you.

Another possible addition is to add a new “egg trap”, which fires eggs at you with the intention of getting egg on you.

Cancelled monsters can quaff potions of restore ability to uncancel themselves.

Monsters apply mirrors at you if you are a nymph or umber hulk.

Drinking multiple potions of booze in a short time span has progressive effects: first confusion as normal, then vomiting, then sending the drinker to sleep or losing some (resistable) HP via alcohol poisoning. Also add in monster (dwarf, orc, leprechaun) booze-drinking behavior, complete with drinking songs as level sounds when a monster is intoxicated.

Monsters carrying food will eat it when at low health and get healed by it.

Vary the monster AI for using miscellaneous items; some monsters like trolls are “hoarders” and will not use misc items unless there is a compelling reason to do so; others will use them at the first opportunity.