IMO 'Arcane Slot builds' are still kind of a meme, though Dragon Pole and Explosive Ward are making them workable sub-themes, albeit in opposite directions.

That said, the biggest perk here is taking enemies out of play, especially in 4 Player games, where you burn through encounter cards at a fast clip. You'll run out of health or sanity, or bullets in your gun, and when faced with Alert or Retaliate keywords, the worst enemies become huge action sinks over time, outpacing many treacheries. Some treacheries exist specifically to throw them right back at you. The Jar lets you shove the most annoying of them in something like Diana's basement, but for monsters. It's the hardest "screw right off" to the horrors since Bury Them Deep. Eat lonely Deep Ones, spammy Snakes, and dancers in the void. The biggest downside is having to be present for the monster's original death.

As of its release, this is probably the most straightforward and effective damage healing in the game, ahead of Earthly Serenity. Basically does what an entire First Aid would do, in one action with no resources, at the cost of temporarily dropping a clue you probably picked up with action compression (Deduction, Fingerprint Kit, Trish) anyway.

Being flexible enough to patch up a Beat Cop, Grete or Bystander is a plus.

This is a pretty incredible card. Over 9 campaigns, you start to notice that the game often presents specific configurations of scenario mechanics that can all get bodied by a boot in the door:

• A scenario climax with one or two key locations, guarded by scary enemies or effects, that can be cleared by emptying out a high-shroud room (sometimes with a narrative shift or bonus for doing so instead of killing the enemies).
• Optional high-shroud challenge rooms with Victory 1 or Victory 2 attached.
• Rooms with incredibly high shroud values you can only hope to investigate by either following specific mechanics or making specific sacrifices (horror, card discards, clue expenditures).
• Needing to spend many clues for a certain effect, with a room that infinitely replenishes clues.
• Enemies or card effects tied to the shroud value of a room.
• New, in The Scarlet Keys: performing non- tests against a room's shroud value.

This is up there with First Watch in the vein of 'great Guardian utility cards your Fighter will struggle to squeeze 2-4 of into their deck'. And it's a level 0 event, so even the Tony brand of deck building can run it. You might think you specifically need high base to make it work, but almost any teammate wouldn't mind throwing one of their UCs in to the test. A good Mystic will reserve a Promise just for this; a good Rogue will wonder why Skeleton Key even exists.

Hello, I was wondering ...
Can you play or activate fast card between the actions of grappling hook? .

Some extra details for □□□ Impulse Control : If you start the game with 2x Honed Instinct at first, when you spend 3 XP to check the boxes, the 3rd copy can come in and replace any card in the deck for free, with the special customizable rule that came with the Investigator Expansion box (see below).

This rule also allow not including any Honed Instinct at first, then spend 3 XP (or more, like one of the □ customization) to swap in all 3x Honed Instinct with the customization into the deck at once. (e.g. If you think 3 cards deck space should be for something better than a base Honed Instinct.)

An investigator may directly purchase one or more copies of a new customizable card with one or more upgrades by spending only the amount of experience points required to purchase those upgrades. (Doing so counts as purchasing a new card, not upgrading an existing card.)