Gatekeeper is an Action-Duration-Attack card from . It forces other players to Exile any Action and Treasure cards they gain without already having a copy in Exile.
 Official FAQ
- While under this attack, whenever you gain an Action or Treasure that you do not have a copy of on your Exile mat, you Exile the gained card.
- Gaining a card that you do have a copy of on your Exile mat is unaffected, and lets you discard copies from your Exile mat if you want to as usual.
- Other abilities that happen when you gain a card happen at the same time, and you can only put the card on your mat if it has not moved anywhere since gaining it; so you can, for example, use a to put a gained card into your hand, then fail to put it on your Exile mat.
- Gatekeeper only Exiles Actions and Treasures, it does not Exile, for example, .
- It only cares about cards in Exile, it does not care how they got there.
 English versions
|| At the start of your next turn, +
. Until then, when another player gains an Action or Treasure card they don't have an Exiled copy of, they Exile it. || Menagerie
|| March 2020
 Other language versions
 Secret History
The premise remained constant. Some versions always exiled
the card; you'd get back the previous one, so once you had e.g. in exile, gaining would work, you would just technically put one into exile and discard the other one. I never liked that much, plus the card felt too oppressive, so it changed to just not working every other time. Some versions cost , but man you don't want to be under this right away.