When someone dies in Eos, a process known as the samsara occurs. The Samsara is the process in which a soul exits a body and makes its way to Purgatory, a theoretically physical location within the Astral Plane. Samsara occurs in three phases, with each phase making resurrection progressively more difficult.
Exequy
The person has just died, and the soul is preparing to leave the body. The soul is yet to detach from the physical body, and this is the time where resurrection is easiest. This phase tends to run for 6 seconds.
Requiem
The soul is moving towards Purgatory. It has freshly detached from the body, and can still be reintegrated into the body with ample effort. It can also be intercepted by magical devices and processes during this time, such as the Nine Lives Stealer or the devilish Tithe of Fire. This phase tends to run for 1 minute.
Sepulchre
The soul has entered Purgatory, where it is judged by Kelemvor, scribe of the dead. These souls may then be rebirthed, or in rare cases, sent to the hells or Elysium. It can take up to 200 years for a soul to be judged.