Spellbook of jumping
| spellbook of + jumping 
| |
|---|---|
| Appearance | random |
| Abundance | 2% |
| Base price | 100 zm |
| Weight | 50 |
| Turns to read | 5 |
| Ink to write | 5–9 |
| Spell type | escape |
| Level | 1 |
| Power cost | 5 Pw |
| Direction | non-directional |
In NetHack, the spellbook of jumping can be read to learn the spell of jumping. It is a level 1 escape spell, and the spellbook takes 5 actions to read.
Contents
Generation
Wizards may be given a spellbook of jumping as the secondary spellbook in their starting inventory.[1]
Spellbooks of jumping make up 1⁄50 (2%) of all spellbooks randomly generated on the ground, in general shops or as death drops. Second-hand bookstores and rare books stores can also stock spellbooks of jumping.
An aligned priest can be generated with the spellbook of jumping as one of their spellbooks.[2]
Writing a spellbook of jumping with a magic marker uses up 5 to 9 charges.
The following information pertains to an upcoming version (NetHack 3.7.0). If this version is now released, please verify that the information below is still accurate, then update the page to incorporate it.
Per commit 319dfbda and commit 495a1a9b, non-pauper Wizards start each game with knowledge of the appearance for the spellbook of jumping.Description
When successfully cast, if the hero is not blocked from jumping, then the spell allows the hero to select a target square that they can directly see, i.e. they cannot be blind[3][4]—if a valid square is selected, then the hero will jump towards it, passing over any traps between them and their destination. If a monster is in the hero's path, they will risk bumping into it, and colliding with a peaceful monster will turn it hostile. A hero that uses the #jump extended command and lacks any innate jumping ability (i.e. they are not a Knight or wearing jumping boots) will attempt to cast the spell of jumping if they know it.[5]
The distance that a hero can jump using the spell is dependent on their skill in escape spells:
Unskilled ........... |
Basic ........... |
Skilled ........... |
Expert ........... |
Jumping through the spell also has a different set of limitations from other means of jumping:
- A hero can jump via the spell even with encumbrance, low strength, low nutrition levels, or wounded legs.[6][7][8]
- A hero can jump via the spell even if they are polymorphed into a form that has no legs or is slithy.[9]
- A hero can jump via the spell even if they are riding a steed that is currently asleep, paralyzed, or otherwise immobile without being stuck in a trap.[10]
- A hero casting the spell cannot use it to pull free from a monster that is sticking to them.[11]
The spell will not allow a hero to jump while they are engulfed, submerged in a pool or moat, or riding a steed that is stuck in a trap[12][13][14]—it will also not allow them to jump while levitating, and will always fail on the Plane of Air or Plane of Water.[15] Casting the spell will always use up energy and nutrition even if the hero cannot jump, but jumping via the spell will consume up to 25 points of nutrition only if the hero is able to select their destination square, regardless of whether or not they reach it successfully.[16] Jumping and selecting a destination in Sokoban incurs a -1 luck penalty regardless of whether or not they reach it.[17]
After selecting a destination, the hero's path towards it is determined by a version of Bresenham's line algorithm:[18][19] this path will be as close to a straight line as possible, but will tend to move the hero along the longer axis of the jump, and will never move them a greater proportion of the distance along the shorter axis than it has moved them along the longer axis. The following diagrams illustrate the non-trivial and asymmetrical paths for jumping to certain squares:
......... ......... ......... ...X.X...
......... ...X.X... ..X...X.. ...*.*...
...X.X... ...*.*... .X.*.*.X. ....*....
..X.*.X.. .X*.*.*X. ..**.**.. X*..*..*X
...*@*... ...*@*... ....@.... ..**@**..
..X.*.X.. .X*.*.*X. ..**.**.. X*..*..*X
...X.X... ...*.*... .X.*.*.X. ....*....
......... ...X.X... ..X...X.. ...*.*...
......... ......... ......... ...X.X...
Jumping while the hero is inside a normal pit or spiked pit both restricts them to adjacent squares and allows them to jump out of the trap.[20] Jumping while the hero is trapped in a web will tear them free of the web and destroy it.[21] Jumping while the hero is trapped in lava will not move the hero from that square, but will reset the timers for escaping and sinking into the lava unless the hero has levitation or flying to keep them free of the lava afterward.[22] Jumping while the hero is stuck in the floor (e.g. from cooling lava they were in) or tethered to a buried heavy iron ball by an iron chain will not move them fromo their square, and will also injure both of their legs for 11–20 turns.[23] Jumping while the hero is caught in a beartrap will free them from the trap, but also deals up to 10 points of damage (subject to half physical damage) and wounds the leg closest to the side they jumped towards for 500–1499 turns.[24]
Strategy
Jumping is a level 1 escape spell, and thus the best choice for enhancing that spell branch. (Do not practice jumping in Sokoban, though!) There are very few places where an unpleasant trap will be placed in an unavoidable position (although the back entrance of the Castle is a notable one), but for those situations it is generally useful; note that some types of trap, such as the fire trap, cannot be bypassed by jumping. It finds some use in speed ascensions, where the small speed boost is critical; jumping actually goes faster than speed boots, although the nutrition burn rate is too high to sustain it for long periods of time. Note that as jumping ends the turn rather than just costing one action, though, continuously jumping means you will see no benefit from speed.
In lit areas, or if carrying a light source, jumping makes for an excellent escape, whether on its own or combined with a wand of teleport for escaping from surrounding mobs of monsters. This is a particularly useful strategy on the Astral Plane, where the nutrition cost is mostly irrelevant and there's no further area to preserve teleport charges for. This is most commonly done with jumping boots, but the spell has slightly more range; it is probably not enough to make up for the Pw cost, though, leaving the boots as the superior source if you don't need the slot for speed boots.
Jumping also helps cross certain special levels, notably Medusa's Island; although not a solution for crossing watery levels in general, it will allow you to get as far as the Castle, and possibly even enter it if you have a wand of striking or similar method of destroying the drawbridge. You can then wish for a ring of levitation or a similar permanent solution to traversing water. Make sure you have some method of detecting underwater creatures (warning works well) before trying this; being attacked by a giant eel or electric eel can end your game almost instantly, and colliding with an underwater creature while in midair (which is possible) can cause you to fall into the water, with all the usual negative effects.
As of NetHack 3.6.2, Barbarians may be interested in learning the spell, since they can now advance skill in escape spells, allowing them to potentially apply the above strategies and/or train their special spell, haste self.
References
- ↑ src/u_init.c in NetHack 3.6.7, line 169
- ↑ src/priest.c in NetHack 3.6.7, line 264
- ↑ src/apply.c in NetHack 3.6.7, line 1662
- ↑ src/apply.c in NetHack 3.6.7, line 1748
- ↑ src/apply.c in NetHack 3.6.7, line 1668
- ↑ src/apply.c in NetHack 3.6.7, line 1723
- ↑ src/apply.c in NetHack 3.6.7, line 1726
- ↑ src/apply.c in NetHack 3.6.7, line 1729
- ↑ src/apply.c in NetHack 3.6.7, line 1678
- ↑ src/apply.c in NetHack 3.6.7, line 1687
- ↑ src/apply.c in NetHack 3.6.7, line 1710
- ↑ src/apply.c in NetHack 3.6.7, line 1690
- ↑ src/apply.c in NetHack 3.6.7, line 1697
- ↑ src/apply.c in NetHack 3.6.7, line 1743
- ↑ src/apply.c in NetHack 3.6.7, line 1716
- ↑ src/apply.c in NetHack 3.6.7, line 1821: this line is only reached if a destination is chosen
- ↑ src/apply.c in NetHack 3.6.7, line 1817
- ↑ src/apply.c in NetHack 3.6.7, line 1811: calls walk_path() in dothrow.c, which contains the algorithm
- ↑ src/dothrow.c in NetHack 3.6.7, line 453
- ↑ src/apply.c in NetHack 3.6.7, line 1772
- ↑ src/apply.c in NetHack 3.6.7, line 1775
- ↑ src/apply.c in NetHack 3.6.7, line 1779
- ↑ src/apply.c in NetHack 3.6.7, line 1783
- ↑ src/apply.c in NetHack 3.6.7, line 1763
This page may need to be updated for the current version of NetHack.
It may contain text specific to NetHack 3.6.4. Information on this page may be out of date.
Editors: After reviewing this page and making necessary edits, please change the {{nethack-364}} tag to the current version's tag or {{noversion}} as appropriate.
