Jump Boost

Increases jump height. Reduces fall damage by each level. The player can normally jump up a distance of $1 1/4$ blocks. With Jump Boost I, that increases to $1 15/16$ blocks, and with Jump Boost II, that increases to $2 1/2$ blocks. Negative levels decrease jump height and increase fall damage (which also causes the player to start taking damage from short falls that would normally do no damage); extreme negative levels will eliminate all jumping ability and will cause damage even when stepping off a slab.

Immune mobs
No mobs are immune to Jump Boost.