A Charm refers to a blind-play in which someone plays an unrelated card from their Fourth Finesse Position. For example, if a player's hand is completely unclued, their Fourth Finesse Position is slot 4.
Just like a Bluff, a Charm can only be performed on the very next player.
Some specific 4 Charm interactions apply when playing at max level, which are detailed below.
Interaction Between The 4 Charm and Double Bluffs Where Cathy Has a One-Away-From-Playable Card
As stated in the level 24 section, Double Bluffs have precedence over 4 Charms. However, there is one small exception.
Double Bluffs do not have precedence in the situation where Bob sees that Cathy has a one-away-from-playable card on her Finesse Position.
Here, it is technically possible that Bob will blind-play the exact card that makes Cathy's Finesse Position playable. But since this is so unlikely, we agree that players in this situation should revert to a 4 Charm interpretation if Bob has a Fourth Finesse Position and the requirements for a 4 Charm are met.
For example, in a 4-player game:
Red 1 is played on the stacks.
Alice clues blue to Donald, touching a blue 4 as a Play Clue. (Blue 4 is currently three-away-from-playable.)
Bob sees that Cathy has a red 3 on her Finesse Position.
If Bob has exactly a red 2 on his Finesse Position, then he knows that Alice's clue would work as a 4's Double Bluff.
However, since the red 3 on Cathy's Finesse Position is one-away-from-playable, Bob knows that 4 Charms should take precedence.
Bob blind-plays his Fourth Finesse Position card.
Even when Cathy's card is one-away-from-playable, there are still some situations in which a 4 Charm is invalid, and therefore a Double Bluff can still be executed. Two such situations are described below.
In the case where Bob does not have a Fourth Finesse Position, then a 4 Charm does not make sense. Hence, a Double Bluff can still be triggered in this case.
For example, in a four-player game:
It is the first turn and nothing is played on the stacks.
Bob and Cathy have a red 1 and red 2 on their Finesse Position, respectively.
Alice clues 4 to Donald, focusing a green 4.
Bob sees Donald has a green 2 on Finesse Position. Thus, the green 4 is only two away and a 4 Charm is not legal.
Bob therefore blind-plays his Finesse Position.
Cathy sees that the green 4 was more than one-away-from-playable, and hence was not a valid Bluff Target for a single Bluff. So, Cathy also blind-plays her Finesse Position.
Donald marks his 4 as any 4.
Interaction Between the 4 Charm and the Out-of-Order Finesse
The Out-of-Order Finesse always takes precedence over a 4 Charm or a 4's Double Bluff, because of Bob's Truth Principle.
For example, in a 4-player game:
It is the first turn and nothing is played on the stacks.
Donald's hand is as follows, from left to right: blue 3, red 4, red 1, blue 3
Alice clues red to Donald, touching the red 4 on slot 1 and the red 1 on slot 2. This is a Play Clue.
Bob knows that this could be the truth as an Out-of-Order Finesse. If that is the case, he should clue number 4 to Donald, allowing him to play the red 1. Then, Bob can blind-play the red 2 and the red 3 (into the playable red 4).
Bob knows that this could also be a 4 Charm, since the red 4 is three-away-from-playable and Bob does not see any other red cards on Finesse Position.
However, Bob knows that he should always assume the truth over a lie, so he assumes that Alice intends for an Out-of-Order Finesse.
Normally, after an Unknown Trash Discharge, non-focused cards are known to be "good".
However, what if a player performs an Unknown Trash Discharge where all of the non-focused cards are trash? A Discharge would incorrectly signal that the non-focused cards are useful.
Instead, this should signal a Charm on the very next player.
For example, in a 3-player game:
All of the 2's are played on the stacks.
Alice clues red to Cathy, touching a red 1 on slot 1 and a red 2 on slot 2.
Normally, Bob would treat this clue as an Unknown Trash Discharge. However, if he Discharges, then Cathy will discard the red 1 and mark the red 2 as either a red 3, a red 4, or a red 5, which would be a Lie.
Instead, Bob knows that this signals an Unknown Trash Charm, so he blind-plays his Fourth Finesse Position. It is a blue 3 and it successfully plays.
Sometimes, when giving a number 1 Play Clue for 1's, a Bad Touch is unavoidable. But what if a player does this when a color clue would have avoided a Bad Touch?
If all the non-focused 1's are trash, the clue must be calling for something extra - a Charm on the very next player.
After the Charm occurs, the clued player will know that only the focus of the 1's clue is playable.
For example, in a 3-player game:
Green 1 is played on the stacks.
Alice clues number 1 to Cathy, touching a red 1 on slot 5 and a green 1 on slot 2.
Cathy's hand is, from newest to oldest: yellow 2, green 1, blue 3, purple 5, red 1
Bob can see that Alice could have clued red to only touch the red 1 and avoid a Bad Touch.
Bob knows that this signals a blind-play:
A Finesse Position blind-play would look like a Trash Finesse, which would be a Lie.
A Second Finesse Position blind-play would look like a Trash Push Ejection, which would be a Lie.
A Third Finesse Position blind-play would look like a Unknown Trash Discharge, which would be a _Lie.
Thus, Bob knows this must be a Junk Charm and blind-plays his Fourth Finesse Position. It is a blue 1 and it successfully plays.