The easiest way to come back from the dead is to be a supernatural that does that innately.
A Sin-Eater, a Promethean, a Purified, a Mummy. That isn't really what you are getting at, though.
Many powerful beings in the World of Darkness can bring back the dead.
Powerful Beings who can raise the dead:
Malleus Maleficarum Hunter
- If you keep a Malleus Maleficarum Hunter on hand the Boon of Lazarus can bring back the dead
- You gotta act fast, you have a number of minutes equal to the Malleus's Benediction rating (so <=5)
- won't work on supernaturals, or people who have been chopped in half etc.
- Costs the hunter a willpower dot, and gives the saved a major derangement
- Page 160 of Hunter the Vigil
- (Note: I haven't checked if this has changed in the Hunter Update)
Angels and Spirits (and Demons?)
Rank 4+ Angels and Spirits of Healing get the Resurrection Numen.
And since Angels get it as a Numen, fluffwise something very similar should be available to Demons. I wouldn't give a PC, or NPC that in a Demon campaign.
But it would be fine and great in say a Hunter Campaign.
Resurrection (Page 230 GMC-RU)
This Numen — only available to Rank 4+ angels and spirits
of healing — raises the dead. The Numen costs 10 Essence to use and
the activation roll is penalized by one die per day that the subject
has been dead. Supernatural beings that have already died as part of
their transformation — vampires, mummies and Sin-Eaters — can’t be
resurrected, nor can anyone who died of natural causes. Other
supernatural beings lose their powers when resurrected. Mages become
Sleepwalkers and werewolves, wolf-blooded.
Obligatory: The God Machine can do nearly anything.
May I present the "Resurrection Machine" Infrastructure, that is in my Demon Campaign.
It is a example of some Infrastructure that could bring back the dead. It is my own work, so you won't find it in the book. But just to get you started with thinking about how Infrastructure can help:
At the back of the ICU (intensive care unit), there is one last door. Most doctors think it is cleaning cupboard, though it is unmarked. When the Hospital is really full (say after a natural disaster), it might get found and used. Normally it is used by Psychopomps or Guardians under the God Machines orders.
Inside is what looks to be another fully kitted out ICU room.
Anyone who can "See Through The Cogs" (such as a Demon or a Stigmatic, or someone with Unseen Sense - God Machine), however sees a darker tale.
The backwall of the room is covered in cogs and valves and sprockets.
The IV is connected to(/via) a pipe in the wall, and what is flowing into the patient is not IV fluids but black oil.
Anyone placed in the Resurrection Machine will be restored to life, as they were (Magic and all if they were supernatural).
Including everything from the person who died while hooked into it -- beeep the heart monitor flat lines, followed by a sharp intake of breath beep, beep, beep -- though to Grandma's Ashes.
However when they come back to life, someone else in the hospital dies.
Further, they don't come back unchanged.
Every second point of willpower they would regain, vanishes (It goes to the Machine).
They gain the Destiny Merit which is referred to on page 225 of the GMC-RU: "…characters with the Destiny Merit are always subject to this [the Infrastructure] Condition."
This is likely the Destiny Merit from Mage: the Awakening (p.81) or something very similar. I leave it to your imagination what the God Machine giving the Destiny Merit to a character means.