|Base price||80 zm|
When worn, a cornuthaum provides MC1. Wizards wearing a cornuthaum gain 1 point of charisma and extrinsic clairvoyance; non-Wizards lose 1 point of charisma and have all instances of clairvoyance blocked (whether by intrinsic or by spell). Wizards can enchant cornuthaums to +7, but others can only enchant them to +5.
Since the cornuthaum and the autocursing dunce cap share the same appearance, it is dangerous to blindly wear-test for one; the cornuthaum can easily be distinguished in shops using its base price of 80 zm (compare to 1 zm for dunce caps).
Cornuthaums are among the best helms for a Wizard to use, but are often overlooked in favor of the helm of brilliance, since a potential +4 or +5 bonus to intelligence and wisdom has far more applications in most situations than the cornuthaum's +1 charisma bonus. As a cornuthaum is made of cloth and does not protect rom falling rock traps, Wizards finding one close to the start of the game may even prefer an orcish helm until they can gain a few levels and raise their HP.
However, from that point on and up to the mid-game, a cornuthaum may be much more preferable over a helm of brilliance, since the clairvoyance property is quite useful for navigating the Gnomish Mines and difficult to obtain elsewhere; the only other permanent source of clairvoyance is the Amulet of Yendor. Most early game Wizards also already have enough innate intelligence to cast low-level spells often (especially elven Wizards), and will lack the power regeneration to make much higher-level spells viable for frequent use before obtaining The Eye of the Aethiopica; they may also be able to raise their intelligence via alchemized potions of gain ability if necessary. Conversely, an orcish Wizard will prefer the helm of brilliance from the beginning to boost their intelligence past the racial maximum and achieve hungerless casting.
While the ability for Wizards to safely enchant a cornuthaum to +7 similar to an elven leather helm makes it more enticing, the scrolls of enchant armor required are better spent elsewhere in their mid-to-late game, especially after obtaining the Eye. The cornuthaum's lack of base AC means that a +5 helm of brilliance can provide the benefits of boosted intelligence and wisdom at only 1 less AC than a +7 cornuthaum; patient wizards can also polypile their way to a +6 or +7 helm of brilliance using the aforementioned scrolls and readily-available elven armor.
Prior to version 3.6.0, cornuthaums had an MC of 2, rather than 1.
In general, a cornuthaum makes excellent pet care; it generally grants the highest level of magic cancellation of all armor a large- or huge-sized pet would fit into, and magic cancellation partly substitutes for any intrinsic resistances your pet cannot acquire.
"Cornuthaum" seems to be a term coined in NetHack for folklore's "wizard hat". Cornu is Latin for "horn", and thauma (θαῦμα) is Greek for "miracle, wonder".
The stereotypical wizard hat is a conical blue hat with yellow stars and crescent moons; these shapes are possibly derived from old cabalistic symbols. Variations are seen in folklore, but the hat stays at least vaguely conical. The notion of a thinking hat possibly derives from ceremonial conical hats, or even true thinking hats, making it only natural that wizards wear one.
He was dressed in a flowing gown with fur tippets which had
the signs of the zodiac embroidered over it, with various
cabalistic signs, such as triangles with eyes in them, queer
crosses, leaves of trees, bones of birds and animals, and a
planetarium whose stars shone like bits of looking-glass with
the sun on them. He had a pointed hat like a dunce's cap, or
like the headgear worn by ladies of that time, except that
the ladies were accustomed to have a bit of veil floating
from the top of it.
"A wizard!" Dooley exclaimed, astounded.
"At your service, sirs," said the wizard. "How
perceptive of you to notice. I suppose my hat rather gives me
away. Something of a beacon, I don't doubt." His hat was
pretty much that, tall and cone-shaped with stars and crescent
moons all over it. All in all, it couldn't have been more