You are a Necri, a set of monks who each made a deal with Death to collect stray and escaped souls to send them to the Underworld to go through Hell and be reincarnated. You do not age, thanks to the blessing of Grim.

Age Immunity

You do not age, but still need food and water, and can be killed by regular means.

Dark Affinity

Death's cloak allows you to disappear in shadows and darkness, and you have Darkvision.

Soul of Oblivion

Your unarmed attack does double damage to undead creatures, and you are immune to Necrotic damage.

Reaper's Fury

You can summon two additional sets of arms for one encounter. You can also cast Finger of Death for the duration.