Psi bolt
Psi bolt[1] is a monster spell that appears in NetHack.
Contents
Description
Psi bolt is a melee-range spell that can be used by any monster that casts mage spells, and is only used against the hero. It deals damage depending on the caster's level, as with most standard calculations for monster spell damage: the damage is (ML⁄2 + 1)d6 of damage unless the monster's casting attack specifies any dice, in which can it deals (ML⁄2 + x)dy damage, where (x, y) is the amount and size of the damage dice.[2][3] The psi bolt spell has its damage halved if the hero has either half spell damage or magic resistance, and is reduced to 1⁄4 if they have both properties (rounded up in both cases).[4][5]
The higher the casting monster's level, the less likely that monster is to randomly select that spell: from levels 1 to 23, the odds decrease significantly from 100% to 4.3%. At level 24 and above, however, there is a chance that the touch of death monster spell will be replaced with a psi bolt if the hero has magic resistance or else is hallucinating (since both properties block the spell)[6] - this results in a slight bias of spell choice towards psi bolt, raising the chance to to 12% at level 25 in those cases, and raising them further to about 18% at level 50.[7]
Damage calculation shorthand
Since most monsters have either zero damage dice or 6-sided damage dice for their mage spellcasting attacks, the "base" damage of this spell can reliably be expressed as ml⁄2d6 damage, with additional damage based on the monster that cast the spell: +8d6 for Orcus and Demogorgon, +6d6 for Dispater, +4d6 for Archons and golden naga, +2d6 for ki-rin and +1d6 for other monsters. Neferet the Green is the one exception, with her psi bolt dealing damage equal to (ml⁄2 + 2)d8.
Strategy
Psi bolts from high-level spellcasters can prove to be a major threat in the late game. Though the touch of death is more immediately run-threatening, a strong enough psi bolt can still deal significant damage through magic resistance that would nullify the former spell completely.
History
In NetHack 3.3.1 and earlier versions, including some variants based on those versions, magic resistance reduces damage from the attack to 1, according to a comment in the code.[8]
In NetHack 3.4.3 and earlier versions, including some variants based on those versions, the relative frequency of the psi bolt spell would rapidly increase starting at level 24, passing 50% at level 44.[9] Spellcasting monsters with a very high level would use this spell very often, which could be a high-damage hazard to a hero (e.g. 33d6 base damage for a psi bolt from Demogorgon).
Messages
| Message | Damage dealt |
|---|---|
| "You get a slight <head>ache." | 0-5 |
| "Your brain is on fire!" (not to be confused with intelligence drain) | 6-10 |
| "Your <head> suddenly aches painfully!" | 11-20 |
| "Your <head> suddenly aches very painfully!" | 21+ |
Variants
SLASH'EM
In SLASH'EM, there are many new monsters that can cast mage spells - using the shorthand methods described above, the additional damage values are as follows: +6d6 for ghoul mages, +5d6 for Solars, +4d6 for Planetars and ghoul queens, +2d6 for vampire mages, and +1d6 for all others.
As SLASH'EM is a 3.4.3 variant, high-level spellcasters are very likely to cast psi bolt - this includes Demogorgon and Dispater, who are guaranteed encounters alongside the other demon lords and princes that are optional in vanilla NetHack.
References
- ↑ src/mcastu.c in NetHack 3.6.7, line 10: the spell's name is never used in-game
- ↑ src/mcastu.c in NetHack 3.6.7, line 288: calculations for monster spells cast with damage dice
- ↑ src/mcastu.c in NetHack 3.6.7, line 290: calculations for monsters spells cast without dice
- ↑ src/mcastu.c in NetHack 3.6.7, line 499
- ↑ src/mcastu.c in NetHack 3.6.7, line 292
- ↑ src/mcastu.c in NetHack 3.6.7, line 93
- ↑ src/mcastu.c in NetHack 3.6.7, line 87
- ↑ src/mcastu.c in NetHack 3.6.7, line 497
- ↑ mcastu.c in NetHack 3.4.3, line 83
