A Life Orb is a held item that boosts the holder's damaging attacks by 30%, but causes the holder to take 10% of its maximum HP in recoil with each damaging attack it uses. It can be crafted, and can also be obtained as a tier 3 special drop. It is a possible drop from legendary and ultimate boss Pokémon, or from certain wild Pokémon.
Life Orbs require Nether stars to be crafted. In order to spawn a wither and kill it for a Nether star, wither skeleton skulls are needed. As wither skeletons do not spawn by default in Pixelmon, the skulls are instead dropped rarely by uncommon and rare boss Pokémon.