Typically, the player who receives a clue that causes a Bluff blind-play knows that the card that was clued is one-away from being playable.
Our group plays with an artificial 3 Bluffs convention. This means that in addition to being one-away from being playable, we agree that the touched card can also be any 3 that will be useful in the future.
3 Bluffs are mostly used to get 1's played at the beginning of the game. However, similar to a normal Bluff, a 3 Bluff can be used to get any playable card (as long as it doesn't look like a Finesse, obviously.)
Here are some examples that cover the four most common 3 Bluff situations:
On the first turn of the game, Alice clues Cathy red, which touches a red 3.
Bob blind-plays blue 1.
Cathy knows that it is either a red 2 (if it was a normal Bluff) or a red 3 (if it was a 3 Bluff). She marks down both of the possibilities for later.
Example 2 - Number 3 with Suit Disconnect (Valid)#
On the first turn of the game, Alice clues Cathy number 3, which touches a red 3.
Bob blind-plays blue 1.
Cathy knows that it was a 3 Bluff, because a played 1 does not "connect" to number 3.
Beyond that, Cathy knows nothing about the card, besides that it is a 3 (since it has a number 3 clue on it).
Example 3 - Color Connect (Not Valid; Looks Like a Finesse)#
On the first turn of the game, Alice clues Cathy red, which touches a red 3.
Bob blind-plays red 1.
Cathy sees that Bob does not have red 2. Since red connects to red, Cathy assumes that she has the red 2.
Cathy misplays red 3 as red 2.
Alternatively, if Cathy saw that Bob had both red 1 and red 2 on his Finesse Position at the time the clue was given, she would know that she has the red 2 or the red 3. Subsequently, Bob is promised a red 2, since if he does not blind-play a card, Cathy will go on to misplay the red 3 as red 2.
Example 4 - Color Connect With Rank Disconnect (Not Valid; Looks Like a Finesse)#
This is a 4-player game.
Nothing is played on the stacks.
Alice clues Donald red, touching a red 3 as a play clue.
Bob blind-plays the red 1.
Cathy notices that Donald's red card has a negative 2 clue on it. This means that Donald will not go on to misplay the card as the red 2.
Cathy needs to evaluate whether or not Alice's clue is a Finesse or a 3 Bluff. If this is a Double Finesse, then Cathy needs to blind-play the red 2. If this is a Bluff, then Alice only intended for Bob to blind-play.
Cathy knows that since red connects to red, this must be a Double Finesse, so Cathy blind-plays the red 2 into the red 3.
3 Bluffs can be confusing. If you don't want to memorize the five examples above, you can simply ask the following questions:
Does the clue "connect" to the blind-play? If it connects, then it is a Finesse. If it does not connect, then it is a Bluff. Red connects to red, but red does not connect to blue. 2 connects to 3, but 1 does not connect to 3.
Will the player who received the clue go on to misplay if nothing else is blind-played? If yes, then it is a Finesse. If no, then it is a Bluff.
Building on the 3 Bluffs convention, we also agree that it is possible for a card that initiates a Bluff to be a copy of any of the 4s that are currently in the discard pile, but only if a color clue is used.
For example, in a 3-player game:
Nothing is played on the stacks. Red 4 is currently in the discard pile.
Alice clues Cathy red, touching a red 4 as a Play Clue.
Bob blind-plays a blue 1.
Cathy marks her red card as the one-away-from-playable red card, the red 2.
However, Cathy also knows that 3 Bluffs are a thing, so she also marks her red card as possibly a red 3.
However, Cathy also knows that Critical 4 Bluffs are a thing, so she also marks her red card as possibly a red 4.
Sometimes, it can be ambiguous as to whether a player blind-played a card into a Bluff, or they blind-played into a Finesse + Prompt. In this situation, Occam's Razor applies, so players should go with the Bluff interpretation, since it is simpler. When such a Bluff occurs, it is called a Hard Bluff to disambiguate from situations where Bluffs happen with no ambiguity.
For example, this is a Finesse + Prompt and not a Hard Bluff:
Only red 1 is played on the stacks.
Cathy has a 3 clued in her hand (with no color information on it).
Alice clues Cathy about a brand new 4.
Bob blind-plays red 2.
In a normal Bluff, a one-away-from-playable card is clued. However, Cathy sees that the highest stack is the red stack, so the 4 in her hand must be two-away.
Thus, Cathy does not read it as a Bluff; she is promised red 3 and red 4, so she plays the unknown 3 as a Self-Prompt for the red 3.
For example, this is a Hard Bluff:
Red 1 and blue 2 are played on the stacks.
Cathy has a 3 clued in her hand (with no color information on it).
Alice clues Cathy about a brand new 4.
Bob blind-plays red 2.
This could be a Bluff if the 4 in her hand is blue 4, since blue 4 is currently one-away-from-playable. Thus, Cathy does not assume that her 4 is red 4, and subsequently, does not assume that her unknown 3 is a red 3. However, it could also be the case that the 4 is a red 4 (if the 3 in her hand happens to be red 3).
Thus, Cathy marks down both possibilities for later and does not play anything right now.
Usually, when a Bluff occurs, the blind-playing player has no idea that is a Bluff - they assume they are playing a specific card into a true Finesse.
However, in rare situations, a clue will be given that looks like a Finesse, but the next player will know for sure that they do not have the "connecting" card.
In these situations, if the next player cannot see a better explanation for the clue, then they should blind-play their Finesse Position card as a Known Bluff.
For example:
The player might see all of the copies of the card that they are supposed to be blind-playing.
The player might have negative information on their entire hand (e.g. negative blue on every card when they are supposed to be blind-playing a blue 2).
The player might know that they are blind-playing a 1 into a 3 Bluff (e.g. a card was clued with number 3 and there are no cards played yet).