There is another post which discussed theories on how this effect can be obtained. I was unable to relocate that thread so here goes...
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With no effect applied...
If you are taken down by zombies/ect and another team member revives you.
You loose all perks obtained.
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With added Desired Effect (Tombstone -1)
Once effect is obtained if you are taken down by zombies/ect and another team member revives you.
YOU ONLY LOOSE ONE PERK - Quick Revive if you have it or the last perk obtained.
* This trait once active appears permanent and will function on future matches
- confirmed on multiplayer
- unconfirmed single player games
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How to obtain this effect
A. Player must purchase all 4 perkson round 1
- confirmed = 1st player to 4 perks
- unconfirmed = works for all players not just 1st to 4 perks?
- unconfirmed = It is rumored to work after round 1?
- unconfirmed = Only one player per round can get this?
- unconfirmed = May just need to buy 4 perks in any 1 round to get effect?
B The 4th Perk bought being the Vulture Perk
- confirmed = 1st player to 4 perks & last perk obtained was the Vulture Perk
- unconfirmed = obtaining perks does not require a specific order?
C Quick Revive Perk-
- confirmed = If you do not have QR then the last perk obtained will be dropped.
- confirmed = If QR is one of the perks even if it was not the last perk obtained, It will be the perk lost when you go down.
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NOTE: Possible ways to loose effect.
- Teammate revives with the PAP ballistic knife.