In multi-color variants, Prompts apply to the card with the most positive information.
For example, in a 3-player rainbow game:
Red 2 is played on the stacks.
Alice clues red to Cathy, touching a red 4 as a Play Clue. This is a Prompt on Bob for a red 3.
In slot 1, Bob has a card with only a red clue on it. (Thus, it can be any red card or any rainbow card.)
In slot 2, Bob has a card with a red clue and a 3 clue on it. (Thus, it can be red 3 or rainbow 3.)
Since slot 2 has more positive information, Bob should choose to play slot 2 as red 3 (instead of slot 1, the leftmost card).
Players are not supposed to use information from negative clues.
For example, in a 3-player rainbow game:
Red 2 is played on the stacks.
Alice clues red to Cathy, touching a red 4 as a Play Clue. This is a Prompt on Bob for a red 3.
In slot 1, Bob has a card with a positive red clue on it. (Thus, it can be any red card or any rainbow card.)
In slot 2, Bob has a card with a positive red clue on it and a negative green clue on it. (Thus, it can be any red card.)
Even though slot 2 is technically more likely to be the red 3, Bob knows that players are not supposed to use negative information for determining which card to play into a Prompt. Thus, Bob plays the red 3 from slot 1.
Sometimes, you want to Finesse someone with a clued card already in their hand. However, if you try to Finesse them, they will assume it is a Prompt and will play their clued card. Which means that a lot of the time, you can't give a Finesse, and must instead clue the card directly.
However, what if the clued card actually is playable? In that case, you can still do the Finesse - they will play the Prompted card, see that it wasn't the card you had intended, and then blind-play their 2nd newest card on the next turn. This is called a Hidden Finesse because the Finesse was temporarily hidden by the presence of clued card.
For example, in a 3-player game:
Red 1 and rainbow 2 are played on the stacks.
Alice clues red to Cathy, which touches her red 3.
Bob has a rainbow 3 clued as red in his hand and he has no idea what it is.
Bob sees that Alice's clue must be a Prompt, so he plays his red card as red 2. He is surprised to see that it is actually rainbow 3.
Bob knows that he really must have the red 2, and it must have been on Finesse Position when Alice originally gave the clue. Since he just drew a card after he played the rainbow 3, he now knows that the red 2 is on his slot 2 (the second-newest card).
On Bob's next turn, he blind-plays his the red 2 from slot 2.
In this example, the red 2 was "hidden" by the rainbow 3.
Normally, a Finesse promises the exact copy of the card on Finesse Position. However, as long as all of the cards leading to the card are playable, you can still promise the exact copy of the card. We do not consider this to be a Lie, since the blind-playing player does indeed have the true copy of the card.
We call this a Layered Finesse because the intended Finesse blind-play target is "layered" behind other playable cards.
For example, in a 3-player game:
It is the first turn of the game and nothing is played on the stacks.
Alice clues red to Bob, touching a red 2 as a Play Clue.
Normally, Bob would think that he has the red 1. However, he also sees that this could be a Reverse Layered Finesse on Cathy. Thus, Bob cannot play anything right now - he must wait and see what Cathy does.
Bob does something unrelated.
Cathy knows that this is a Reverse Finesse and that she has the red 1. Cathy blind-plays her Finesse Position card. However, it is actually a blue 1, and it successfully plays. Cathy gasps in surprise.
Alice does something unrelated.
Bob knows that Cathy must have been trying to blind-play a red 1. Thus, he must have the red 2, and Alice did indeed perform a Layered Finesse.
Bob does something unrelated.
Cathy was surprised that she blind-played the blue 1 instead of the red 1. This must be a Layered Finesse and Cathy must really have the red 1. Cathy plays her Second Finesse Position and it is the red 1.
To the player who receives a clue that initiates a Layered Finesse, it is usually obvious what is going on. For example, in a 4-player game:
Alice clues Donald blue, touching one blue card.
Bob discards.
Cathy blind-plays a green 1.
Donald clearly knows that this is a Layered Finesse on Cathy - Cathy will continue to play cards until she finds the blue card that connects to the one in his hand.
In other words, most Layered Finesses cause unrelated cards to blind-play that do not connect to the type of clue given.
With that said, it is also possible to perform a Layered Finesse for unrelated cards that do connect to the type of the clue given. When this happens, it is hidden from the receiver of the clue, so we call it a Clandestine Finesse to disambiguate it from a (more obvious) Layered Finesse.
For example, in a 3-player game:
Alice clues number 3 to Cathy, which touches the red 3 on slot 2. Thus, the red 3 is the focus of the clue. This must be a Play Clue on the red 3.
Bob knows that the red 3 is currently unplayable, so it must be a Finesse. He blind-plays his Finesse Position as a red 2. Instead, it is a blue 2, and it successfully plays. Bob gasps in surprise.
Normally, Cathy would think that she has the blue 3, because that would connect to the blue 2 that blind-played. (Number 2 connects to number 3.)
However, Cathy also sees that Bob had a red 2 on his Second Finesse Position at the time of the clue. So there is a possibility that this was a Clandestine Finesse instead of a normal Finesse. Thus, Cathy has to give Bob a chance to blind-play the red 2. If he does not, then Cathy does indeed have the blue 3.
Cathy does something unrelated.
Alice does something unrelated.
Bob was surprised that he blind-played the blue 2 instead of the red 2. This must be a Clandestine Finesse and Bob must really have the red 2.
Bob blind-plays his slot 2 card. It is the red 2 and it successfully plays. (Bob knows that if he did not do this, then Cathy would go on to misplay the red 3 as a blue 3.)
If a player has been Finessed, then their Finesse Position moves right one slot, exactly like if the blind card was clued. (This is a similar concept to how the chop moves left one slot when a player is Chop Moved.)
Subsequently, it is possible to perform anotherFinesse on a player who has already been Finessed. In this case, then the second Finesse is queued after the first. The player is expected to blind-play into the Finesses in order, from earliest to latest.
The reason for this convention is that it allows Layered Finesses to work properly. In other words, if Bob thinks that he is Finessed twice, he also has to entertain the possibility that he is Layered Finessed once.
Sometimes, the player that is supposed to blind-play a card into a Finesse is ambiguous. For example, in a 4-player game:
Nothing is played on the stacks.
Alice clues Donald about a red 2 as a Play Clue.
Both Bob and Cathy have red 1 on their Finesse Position.
Bob will think that it is a Finesse directed at Cathy, and he will discard.
Next, Cathy thinks that Bob made a mistake and "missed" the Finesse. Cathy discards.
Here, Cathy is actually the one making the mistake. Finesses are considered to be basic moves, so the idea is that you should trust that your teammates are not making a mistake. If Bob is discarding, then it means that Cathy also has the exact same copy of the card, and Cathy should immediately blind-play.
Sometimes, players who have been Layered Finessed cannot blind-play their cards right away. When this happens, they will be giving clues or discarding.
Thus, it is possible for a person who has been Layered Finessed to accidentally give a Play Clue to a card in someone else's hand that was already "gotten" inside of the Layered Finesse of their own hand.
When this occurs, one of two things usually happen:
If Bob (the person who was clued) knows the exact identity of the card, then it is obvious that Alice accidentally duplicated it. In this case, Bob can safely discard the card to pass it back to Alice. (This is important to prevent a bomb later on when Alice "unravels" the Layered Finesse.)
If Bob (the person who was clued) does not know the exact identity of the card, then he is forced into just playing the card. Bob is not allowed to "dick around" in this situation, as that might cause even more confusion for the team. After Bob plays the card, if it was indeed duplicated, then the team must now give a Fix Clue to Alice. At first, Alice will be surprised that a clue is being targeted to a card "inside of her layer". But when combined with the context of Alice giving a clue to a similar card, it should be obvious what is happening.
Urgency Principle (Playing Into Finesses as Soon as Possible)
Normally, when a Finesse occurs, someone blind-plays right away. This is extremely important, because it resynchronizes the information among the team. So, as a group, we agree to blind-play our cards as soon as reasonably possible. This is called the Urgency Principle.
Thus, if you see that a player does not blind-play into the Finesse, then you know that the Finesse must be on you.
However, there are two important exceptions:
Players are allowed to defer playing into a Finesse if they are giving a clue that causes a Finesse (and no-one else on the team could have done it).
Players are allowed to defer playing into a Finesse if they are doing something really important, like saving a 5 on chop or giving a Play Clue to a card that is about to be discarded.
So, if any of the above two conditions apply, then you have to wait and give the player yet another turn to demonstrate whether or not they will blind-play.
For example, in a 5-player game:
All of the 1's are played on the stacks.
There is 1 clue in the bank.
Alice clues red to Emily, touching a red 3 as a Play Clue. This is a Finesse on the red 2.
Bob sees that the Finesse is on Cathy. (Cathy has the red 2 in her Finesse Position.) Since the team is at 0 clues, Bob discards.
Cathy's knows that Alice is performing a Finesse and that she must have the red 2. Cathy's first instinct is to blind-play the red 2. This is urgent because otherwise, Emily will think that her red card might be the red 2, and it would misplay.
However, Cathy also sees that Donald has a blue 5 on chop that needs to be saved. Furthermore, from Cathy's perspective, Donald could discard on his turn, so the blue 5 is in imminent danger. If Cathy blind-plays into the Finesse, then the blue 5 might get discarded.
Instead of blind-playing into the Finesse, Cathy clues number 5 to Donald as a 5 Save.
Since the team is at 0 clues, Donald discards.
After Alice's clue, Emily marked her red card as "red 2 or red 3 if Cathy blind-plays red 2". However, even though Cathy did not blind-play the red 2, Emily could see that Cathy was doing an important, time-sensitive action to prevent the team from losing the game. Thus, Emily knows that she needs to give Cathy another chance to blind-play the red 2. If Cathy does not blind-play the red 2 on her next turn (and nothing else special is going on), then Emily can play her own red card as the red 2.
Often times when you are given a clue, the card could be two or more things. For example:
In a no-variant game, a red Play Clue might indicate a red 2 or a red 3 depending on whether or not red 2 will blind-play from someone else's hand.
In a rainbow-game, a red clue might indicate either a Play Clue on a red 1 or a Delayed Play Clue on a rainbow 2 through another player's yet-to-be-played rainbow 1.
After getting a clue, you should immediately mark all of the possibilities down on the card as a note.
For all of your subsequent turns, you have to treat that card like it is all of the possibilities at the same time. This is a lot like the Schrödinger's Cat quantum physics analogy, which states a cat is both alive and dead at the same time, and you won't know until you actually open the box and look. Similarly, treat the unknown card as all the possibilities at the same time, and you won't actually know until the card is played.
The implications of Schrödinger's Cat Principle is that players must be very careful. Before playing a card, they will often have to wait for everyone else to have a turn to allow for the possibility of a Prompt, Reverse Finesse, and so forth.