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 continual to function on future games.)
- confirmed on multiplayer
- confirmed single player games
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How to obtain this effect
A. Player must purchase all 4 perks in one round (before round 4?) - (This is all that is needed but some other criteria must also be met first for it to activate)
- confirmed = Round one - 1st player to 4 perks (below stats when effect was obtained)
- Had PAP weapon in vault
- Had Money in bank & withdrew enough to buy 4 perks
- Rank - Skull w/ Glowing eyes
- Bought booze and broke last barrier for 4th perk ... Vulture
- Did not buy wall weapon
- Did not hit the mystery box
- semi-confirmed = works for all players not just 1st to 4 perks?
- unconfirmed = Buying Quick Revive as one of the 4 may block the effect from activating on multiplayer?
B. Quick Revive Perk (With Effect Active)
- confirmed = If you do not have QR then the last perk obtained will be dropped when you go down.
- 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.
Other Criteria
It appears that all you need to do is buy all 4 perks in any single round, But some criteria must be met first before you gain access to the effect. What this criteria could be...
- unconfirmed = Need a PAP weapon stashed in weapon vault .(Holding it when 4th perk is purchased?)
- unconfirmed = Need money stashed in Bank?
- unconfirmed = You need to be the player that buys the booze to open a barricade? (All barricades definitely not required)
- unconfirmed = Must reach level X in a previous zombies game? (PAP a weapon in previous game?)
- unconfirmed = Player must reach X level in zombies play? (Skull w/glowing eyes?)
- unconfirmed = Need Glowing Eyes first?
- Disproved = You need to be the player that turns on the power?
- Disproved = Do not buy a wall weapon?
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NOTE: Possible ways to loose effect.
- unconfirmed = Teammate revives with the PAP ballistic knife.
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Ask for testers...
Anyone that wants to aid in ironing this out please try to confirm or discount the Other Criteria list.