Contrary to the other reviews here, I do think this card is quite good.

There are maybe ~18 rounds average on the doom clock in Arkham.

• If your investigator has soak/healing (Tommy, Carolyn, etc) you can use it to straight cancel 2-3 of the worst treacheries you draw (~1/6th of your total in a game!), and transfer some more into random ones (using the 'remove corruption' option, depending on just how much soak/heal you have)
• If your investigator doesn't have soak/healing, you can still use it to cancel 3 bad treacheries and take a random one later (in any fast action window!)
• It makes you more resilient to unfortunate game states, and allows you to maximise your chances:
  • You pull something and have no skill cards in hand (wait until you have a hand, then draw one & heal)
  • You can choose to pull the 'instead' encounter card(s) when grouped up with the team so they can commit if necessary
• You can effectively use it to transfer damage/horror between your investigator card and your allies
• It can save your life — there'll be a fair few occasions when a treachery you draw will do worse than 1-1 to you
• It can buy you extra rounds of the game, in scenarios where Ancient Evils and other 'add doom/can cause agenda to advance' effects are in the encounter deck
• Calvin can use it to take damage/horror quickly and then heal a bit for a fast action when necessary (bonus: I believe the treachery you draw will be tested at your higher stats - i.e. before healing - because it's part of the cost)

TL;DR is bad encounter deck pulls at the wrong time is the easiest way to tank a scenario (possibly the only way for a lot of us), and something most investigators don't really have much say over... at least until now (neutral, asset with uses). Straight cancelling is super powerful if you can afford the cost here, and if not then transferring a bad treachery for a random one at a time of your choosing is also strong. It's expensive, but worth a look.

So first off I don't think this card is very good. 4 cost 4 xp is extremely high and most people would rather not take 1 and 1.

However there are two different decks which may be interested?

Tommy with Spiritual Resolve might be interested in three instances of 1 and 1. Same with anyone who has Peter Sylvestre and Jessica Hyde out -- that turns this card effectively into "skip the next three encounter cards you draw", which is very good.

I personally can't see why you'd ever want to activate the fast ability. Maybe there's something I'm missing here. I guess Tommy or Calvin can use this combo to just take 1 and 1 whenever they want, since nothing exhausts. Not exactly a mind blowing combo but it's something?

While normally trading one encounter card only allows the ability to swap an especially bad treachery for a random one, another potential use case for this card is when the group has mythos scanning such as Alyssa Graham and wants to be able to give the top encounter card to someone who isn't first player. E.g. the lead investigator is a Guardian or Rogue and the other investigator is a mystic who sees Rotting Remains on top of the deck.