Spellbook of jumping
| spellbook of |
|Base price||100 zm|
|Turns to read||3|
|Ink to write||5–9|
|Power cost||5 Pw|
This spellbook allows you to learn the jumping spell, allowing you to pass over unavoidable traps and escape too-tough monsters; however, you cannot jump over monsters ("You bump into foo."). For more information on whether a given jump will bring you in contact with a monster, see Jumping#Path. Casting jump consumes d25 nutrition, in addition to the ordinary hunger penalty. Advancing Escape spells allows you to jump farther, as is shown:
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. 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 (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 (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 even to enter it if you have a wand of striking or similar method of destroying the drawbridge), where you can wish for a ring of levitation or similar more 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.
Note that some types of trap, such as the fire trap, cannot be bypassed by jumping. Also note that you must be able to see the landing area, so jumping will fail when blind.