Much as in real life, hallucination will cause you to perceive objects in a distorted fashion. Hallucination changes the appearance of both monsters and objects. You can easily cure hallucination with a unicorn horn.
Any objects will be seen as continually changing items of any class, so a pick-axe may be seen as a sack or dagger, but not as a monster. This perception changes every time the screen is updated, so even selecting the object and pressing ; to see what it is appearing as will change it to something else.
One of the most dangerous things about hallucination is that it conceals what the actual monster is, hiding its peaceful/tame status from you as well. An easy mistake is to start hallucinating in a melee situation and lose track of which monster is your pet (easy to do when every monster appears to change every turn) and accidentally kill it.
Don't bother trying to engrave anything while hallucinating - you almost certainly won't manage to engrave what you intended to.
The set of names chosen for monsters while hallucinating includes a selection of rather funny creatures, which will never be generated in the game. These include Barney the Dinosaur, King Kong, the Luggage, and the Mother-in-Law, as well as The Ravenous Bugblatter Beast of Traal among others.
Similarly, hallucination replaces standard messages with funny ones, such as "Welcome to experience level 4. You hear the studio audience applaud!" and "You are getting the munchies.". (see Hallucinatory messages)
Hallucination abuses wisdom.
Hallucination shows up on the status line as a status effect saying "Hallu".
Hallucination has the odd effect of protecting against the touch of death attack. Instead of dying, "You have an out of body experience." It does not protect against Death's special deadly touch attack.
Items the player is currently standing on are not subject to hallucinogenic effects. If you kill a hallucinogen-distorted monster and step onto the square containing its corpse, the corpse will be accurately identified. This holds for other objects as well. Items in the user's inventory are also not subject to the effects. Also, the hero's sense of taste is not distorted, the hero is able to accurately identify what is in a tin by eating it (but as noted above, you may hallucinate the wrong smell before eating it).
There are a few ways to hallucinate:
- eat the corpse of or a tin of yellow mold or violet fungus, or any monster with a stunning attack (lasts 200 turns)
- be subject to the explosion of a black light (lasts 10d12 turns)
- quaff a potion of hallucination (lasts 300-499 turns for blessed, 600-799 turns for uncursed, 900-1099 turns for cursed potion)
- have a glass orb zap your mind (1/5 chance, lasts 1-100 turns; otherwise may cause other ill effects)
- apply a cursed unicorn horn (1/6 chance, lasts 1-100 turns; otherwise causes other ill effects)
- container trap: "A cloud of <color> gas billows from the large box." (unless the container trap is harmless, there is 3/26 chance of this effect, lasts 16-20 turns; otherwise may cause other ill effects)
- <color> is replaced with either ultraviolet, infrared, bluish-orange, reddish-green, dark white, light black, sky blue-pink, salty, sweet, sour, bitter, striped, spiral, swirly, plaid, checkered, argyle, paisley, blotchy, guernsey-spotted, polka-dotted, square, round, triangular, cabernet, sangria, fuchsia, wisteria, lemon-lime, strawberry-banana, peppermint, romantic, or incandescent.
If you are already hallucinating, your hallucinating period increases by this number of turns.
Hallucination can be cured by:
- applying a noncursed unicorn horn
- quaffing a potion of sickness, potion of extra healing or potion of full healing
- praying (considered a minor problem)
- just waiting it out
Wielding Grayswandir makes you hallucination-resistant, but is not a cure: For each turn that you're wielding Grayswandir, the effects of hallucination are negated. Un-wielding the sword will cause you to begin (or resume) suffering the effects, and wielding it again will toggle the effects back off. If you're wielding Grayswandir when hallucination wears off, you receive the message "Your vision seems to flatten for a moment but is normal now."
Once you have a noncursed unicorn horn, hallucination is trivial to cure. Until then, you may wish to refrain from quaffing unidentified potions unless you have a safe way of curing hallucination. It is easy to avoid the other causes of hallucination except for an exploding black light. If you are aware of the light's approach (e.g. through see invisible, monster detection or noticing your pet fighting something invisible) you can blindfold yourself so that the explosion has no effect. Failing that, hallucination from a black light only lasts for approximately 100 turns, so you can shut yourself in a room and wait it out.
If you have quaffed a potion of hallucination and have no way of curing yourself, it is wise to leave your pet behind and stay away from large concentrations of peaceful monsters. Do not try to explore Minetown, and stay out of the Gnomish Mines if the dwarves or gnomes are peaceful.
A stethoscope while misidentifying the monster type, will correctly identify its attributes. Thus it can be useful to determine if a monster is tame or peaceful before attacking.
You can identify your pet - or at least that a creature is a cat/dog by using #chat. Its response will be normal for its type.
In SLASH'EM, hallucination also distorts items you are standing on and your inventory, which makes it a crippling disability; however, it is still only a minor problem in the eyes of your deity. It is therefore essential to avoid quaffing a potion of hallucination without a cure, and to remember the inventory letter of your unicorn horn or other remedy.