When consumed, the Cursed Apple does quite a few things.
First, all players within 20 blocks of the player who ate the apple will get Darkness and Slowness for 2.5 seconds, and hear a sound effect.
Then, the consumer of the apple will lose a life, or if at one life 15 rep, then gain Strength I and Regen II for 15 seconds, and Absorption I for 1 minute.
The Cursed Apple can be crafted with the following recipe:
Experience Bottles can be obtained by right clicking on an enchantment table with a bottle.