Mercurial
A mercurial item is an item in dNetHack that is made of a rare material. It spawns incredibly rarely in certain monster inventories or late-game locations, and cannot be wished for. Mercurial items have differing properties depending on the wielder's sanity, insight, and potentially alignment.
The term "mercurial" is only used internally and in wizard mode wishing, with the actual "name" of the material being chaos stuff - for the sake of maintaining clarity, this article uses "mercurial" to refer to the material itself. In-game, mercurial weapons are also described using the name of their current form (see below).
Generation
Mercurial items do not spawn naturally as part of normal item generation. There are currently only three ways to obtain any: certain late-game monster inventories, in the box containing your 'starting kit' in the Madman quest for female half-dragons, and by wishing for the Sky Reflected artifact. Currently, all possible mercurial items are weapons - there are no special effects for non-weapons either, and mercurial as armor is more or less identical to generic metal albeit slightly heavier.
Very few monsters can randomly possess mercurial gear. There is a single monster that is guaranteed to spawn with them, a Jrt Netjer, and a handful of monsters that each have a 1⁄100 chance to have one of their weapons made mercurial. Jrt Netjer do not spawn randomly, and are only found trapped in 1⁄20 of hell vaults. They always spawn with a blessed anarchic mercurial khopesh.
The monsters that can have their weapons randomly made mercurial are orcs of the ages of stars, deminymphs, lilitu, dokkalfar eternal matriarchs, and mariliths. Deminymphs spawn with a random role-based equipment set, and approximately 7⁄8 of their equipment sets have a chance to have a mercurial weapon. All monsters but mariliths have only one weapon this chance can apply to, and mariliths have the chance rolled for every one of their 6 weapons.
Half-dragon madpeople that start the game as female are implied to be descended from a Zerth, a kind of githzerai monk from D&D lore. They always get a random mercurial weapon into a specific box on the goal level of their quest. This weapon is randomly selected from the following list: broadsword, long sword, two handed sword, katana, tsurugi, spear, trident, mace, morning star. For more information on them and their kit, please see the Madman page.
Lastly, the only non-chance based way for all other builds to access a mercurial item is to wish for the Sky Reflected, a mercurial artifact. The Sky Reflected is normally a malleable artifact, capable of be named from any base item type as long as that item is mercurial. However, since no items can be wished for as naturally mercurial, it can only be wished for as a broadsword, it's default state. The Sky Reflected can be merged into the Amalgamated Skies, another mercurial artifact, but only the Sky Reflected can be wished for. Neither artifact can be gifted.
Effects
All mercurial items share certain properties. The enchantment will slowly self-enchant back up to a certain threshold - +0 below experience level 3, +1 at below level 10, +2 at below level 18, and +3 at level 18 or above. This only applies when wielded or worn by the player. In addition, all mercurial weapons count as "fast" when wielded a player or monster above level 9, costing only 5⁄6 of the normal movement cost to attack with (10 vs. 12) when wielded in the main hand or worn as gloves (i.e. not when off-handed). All mercurial weapons apply a minor spellcasting success chance bonus, similar to a robe, when wielded. Mercurial weapons gain double to-hit bonus from enchantment.
Lastly, if the player is chaotic, void-aligned, or unaligned, then all mercurial items deal bonus damage to chaos-hating monsters (lawful monsters, priests and minions of lawful gods, and uvuudaums). It does not matter if the player is wielding the mercurial item. The bonus damage is 1dX, where X is the lowest out of the monster's alignment, and the player's alignment record, level, intelligence, wisdom, and charisma (min 1). As usual for a damage bonus against material-hating monsters, this bonus is not applied to lit lightsabers, since the material is for the hilt, not the blade.
In addition to this, mercurial weapons take on different forms depending on the wielder's current sanity and veil status. Insight past a pierced veil does not affect the form taken, but may apply to effects of each form. When wielded by monsters, they take different forms based on the wielder's encouragement and tameness instead.
The table below shows the primary effects for each form at various experience levels. There are four different level brackets - below level 3, below level 10, below level 18, and 18 or above. This checks against the current wielder's level rather than specifically the players. The sub-rows list the bonuses per column by experience level. Each tier of effects replaces the previous tier, they do not stack.
| Condition | Form | Base damage adjustment | AC bonus | Casting cost bonus |
|---|---|---|---|---|
| Not in your inventory or a monster's inventory e.g. on the ground or being thrown |
Melting | Only deals 1d2 damage | None | None |
| You: Veil lifted and 80 or more sanity
Monster: 3 or more encouragement |
Streaming | Below level 3, applies a penalty of -4 to die size for weapon base damage. | None | None |
| Below level 10, applies a penalty of -2 to die size for weapon base damage. | +1 AC | 1st level spells cost 80% base energy cost to cast | ||
| None | +2 AC | 1st level spells cost 50% base energy cost to cast, 2nd level spells cost 80% base energy cost | ||
| At level 18 or above, applies a bonus of +6 to die size and +1 to the number of dice rolled for weapon base damage. | +3 AC | 1st level spells cost 50% base energy cost to cast, 2nd level spells cost 50% base energy cost, 3rd level spells cost 80% base energy cost | ||
| Not Streaming or Kinstealing | Chained | Below level 3, applies a penalty of -4 to die size for weapon base damage. | None | None |
| Below level 10, applies a penalty of -2 to die size for weapon base damage. | +1 AC | 1st level spells cost 80% base energy cost to cast | ||
| None | +4 AC | 1st level spells cost 80% base energy cost to cast, 2nd level spells cost 80% base energy cost | ||
| At level 18 or above, applies a bonus of +6 to die size to weapon base damage. Increases the number of dice rolled for base damage by 1. | +6 AC | 1st level spells cost 50% base energy cost to cast, 2nd level spells cost 50% base energy cost | ||
| You: Less than 50 sanity
Monster: Negative encouragement (discouraged) |
Kinstealing | Below level 3, applies a penalty of -3 to die size for weapon base damage. | None | None |
| Below level 10, applies a penalty of -2 to die size for weapon base damage. Increases the base damage by 1 flat damage per die rolled. | None | 1st level spells cost 80% base energy cost to cast | ||
| Below level 18, applies a penalty of -3 to die size for weapon base damage. Doubles the number of dice rolled for base damage. | +1 AC | 1st level spells cost 80% base energy cost to cast | ||
| At level 18 or above, applies a penalty of -3 to die size for weapon base damage. Triples the number of dice rolled for base damage. | +2 AC | 1st level spells cost 50% base energy cost to cast |
"Wet" forms of mercurial weapons (streaming and melting) have a 1⁄10 chance of applying hallucination poison to any target they hit.
In addition to their normal damage types, streaming weapons count as slashing, and kinstealing weapons count as piercing.
Insight effects
All mercurial weapons count as insight weapons, gaining additional to-hit and damage dice when used by Madmen or any role with Ose bound.
Independently, each form (except melting) also has three insight-gated effects. Each set of effects is unique to a single form, and unlike many other insight-gated weapons, when wielded by a monster, they use that monster's attributes to determine eligibility. All of these effects are only enabled for chaotic players or monsters, or unaligned (not void-aligned) players. Monsters need to be insightful, i.e. they either grant insight when slain or naturally see beyond the veil, to use any of these effects. For players, binding Ose or Miska will also enable these effects without requiring you to be chaotic or unaligned - Miska aligns you sufficiently to chaos, and Ose allows you to grasp what you previously couldn't.
Streaming weapons begin to deal extra attribute-based damage and attack extra squares behind the target. Above 20 insight, wisdom, intelligence, and charisma grant extra bonus elemental damage, applied as artifact bonus damage (so stacks additively with other damage bonuses). Each die deals a random element from fire, cold, shock, or acid. The die size is equal to (sanity + insight)/10 if the attribute is at 25, (sanity + insight)/20 at 18 or above, or (sanity + insight)/40 at 15 or above. No bonus is given for attributes of less than 15. For monsters, these dice are always equal to the monster's level / 5. This damage does not damage inventory items. In addition to the elemental damage, when at both above 20 insight and above level 20, streaming weapons hit the square behind the target as well. Above 60 insight, hits two squares behind the target, for a total of 3 squares in a straight line. For monsters, they must be above level 20 or 40 respectively to trigger this effect.
Chained weapons begin to drain energy, potentially cancel monsters, and deal extra damage based on weight. At above 20 insight, this drains energy from targets, increasing their spell cooldown by 1d(insight⁄10), using attacker level instead of insight when used by a monster. Against the player, drains the same amount of your energy. At above 40 insight this effect can crit, reducing the player's current energy by 400 instead and forcibly cancelling monsters. They do not get a save to resist this effect. On top of the energy draining, this also deals extra damage based on the wielder's current carried weight. This is equal to 1d(weight⁄160), capping at 80.
Kinstealing weapons begin to drain levels, shred armor, and steal items. The chance to drain one level is (Insanity + Constitution - defender level)⁄100 when used by the player, and replaces your insanity (lost sanity) and constitution with the attacker's level when wielded by a monster. This insanity check respects clear thoughts, and this level drain has no effect on drain-resistant monsters. It also cannot kill targets by reducing their level to 0. The armor shred functions similarly - the chance to apply is (Insanity + Strength - defender level)⁄100 with the same replacement when wielded by monsters. This insanity check ignores clear thoughts, and the shred damage done is 1d(2 per madness you have + 1). When used by a monster, this is always 1d3. Lastly, the item theft is a (Insight + Dexterity - defender level)⁄100 chance, again replacing your modifier with their level when used by a monster. This always steals 1 item, has a 90% chance to ignore wielded weapons, and cannot steal other worn items.
