Several types of "useless" clues trigger a Double Ignition. These different types are listed below.
When a Double Ignition is triggered, it means that two players on the team need to blind-play their Finesse Position as any playable card.
Similar to an Ambiguous Finesse, an Ambiguous Double Ignition is possible. Specifically, this means that three or more players have a playable card on Finesse Position. In this situation, we strongly define who is supposed to be blind-playing:
The first Ignitionmust always be on Bob, unless Bob has a known-playable card already. Then, it would be on the first player that does not already have a known-playable card.
The second Ignitionmust always be on the last player with a playable card.
When a player re-clues a globally known playable card, it is a "useless" clue.
Usually, when this occurs, it is because a player is in a stalling situation and cannot discard. (This is most common in the End-Game.)
If a player is not in a stalling situation, then they must be trying to send a deeper message - a Double Ignition. This is called a Replay Double Ignition because you are re-giving a Play Clue.
The Replay Double Ignition must not introduce any new cards as part of the clue.
The Replay Double Ignition can be performed all throughout the game. (Conversely, the Trash Double Ignition can only be performed towards the end of the game.)
Sometimes, players perform a Trash Chop Move by cluing known-trash in another player's hand (off chop).
However, players can know that Trash Chop Move is impossible if:
they are not the clue-receiver and they can see that the Chop Moved card is bad
they are the clue-receiver and they can determine that they are no cards left to Chop Move (meaning that all of the cards are accounted for, or all of the remaining cards could be given a direct Play Clue or a direct Save Clue).
If the known-trash clue cannot be either of these two things, then it communicates a Trash Double Ignition.
Players should always assume a Trash Double Ignition over a Bad Trash Chop Move Ejection, since the latter is very rare. (Bad Trash Chop Move Ejection is an advanced move that is covered later on.)
When a player re-clues a globally known-trash card, it is a "useless" clue.
Usually, when this occurs, it is because a player is in a stalling situation and cannot discard.
If a player is not in a stalling situation, then they must be trying to send a deeper message - a Double Ignition. This is called a Poke Double Ignition because by re-touching a trash card, it is like you are poking the player.
The Poke Double Ignition must not introduce any new cards as part of the clue.
The Poke Double Ignition can be performed all throughout the game. (Conversely, the Trash Double Ignition can only be performed towards the end of the game.)
The Chop Move Ignition (CMI) (with 1 card Chop Moved)
If a playable card is on chop, the natural thing to do is to give it a Chop-Focus Play Clue. If a player Chop Moves the playable card instead, this is very strange. If there is not a good reason to do so, then the cluer is trying to communicate something extra.
In this situation, they intend for an Ignition on the next player. Since a Chop Move causes a blind-play, the Chop Moved player will know that the Chop Moved card is playable.
For example, in a 4-player game:
It is the first turn and nothing is played on the stacks.
Cathy's hand is, from newest to oldest: blue 4, blue 4, blue 5, red 1
Alice clues number 5 to Cathy, touching a blue 5 on slot 3.
It is now Bob's turn. Bob sees that since there were other Play Clues for Alice to give, Cathy will interpret this as an Early 5's Chop Move.
Bob also knows that it is nonsensical to Chop Move a playable red 1 - Alice could have just give a red Chop-Focus Play Clue to the red 1.
Thus, this must be a Chop Move Ignition. Bob blind-plays his Finesse Position card. It is blue 1 and it successfully plays.
At first, Cathy thought that Alice's clue was a Early 5's Chop Move. However, if that was the case, then Bob would not have blind-played anything. Since he blind-played his Finesse Position card, this must be a Chop Move Ignition. Cathy blind-plays her slot 4 card (the card to the right of the clued 5).
Sometimes, it can be useful to Chop Move a playable card. Something is only a Chop Move Ignition if there is not some other good reason for the Chop Move. Specifically, the player might want to:
Avoid violating Good Touch Principle.
Save a Delayed Playable card that is followed by a critical card.
Get a blind-play from Elimination when the duplicate is visible.
In general, Chop Move-related clues are turned off as soon as there are no cards left to Chop Move. Specifically, this means one-away-from-playable cards that cannot be given a direct Play Clue or Save Clue. Thus, if there are no cards left to Chop Move, a Chop Move Ignition would transform into something else, like a Play Clue or a Double Ignition of some sort.
Interaction Between the Chop Move Ignition and 5 Rank Clues
Normally, a number 5 rank clue to a 5 that is one-away-from-chop would be either:
a 5 Stall
a 5's Chop Move
a Play Clue on the 5
If a 5 Stall is impossible (i.e. it is not a stalling situation), then a 5's Chop Move on a playable card would normally be treated as a Play Clue on the 5.
However, for level 21 players, Play Clues like this are turned off. In other words, every number 5 clue that focuses a 5 that is exactly one-away-from-chop would always be a 5's Chop Move. This is referred to as the Chop Move Ignition Interaction.
The Chop Move Ignition Interaction can be tricky for players, since Chop Move Ignitions can look like normal Finesses. Players need to remember that the blind-play relates to the card being Chop Moved, not the 5 directly.
For example, in a 3-player game:
It is the Mid-Game.
Red 3 is played on the stacks.
Cathy's hand is, from newest to oldest: blue 4, green 3, blue 4, blue 5, blue 1
Alice clues number 5 to Cathy, touching the blue 5 on slot 4.
Bob expected Alice to clue number 1 to Cathy. Thus, this must be a Chop Move Ignition. Bob blind-plays his Finesse Position card. It is red 4 and it successfully plays.
From Cathy's perspective, she first thought that Alice's clue was a 5's Chop Move. However, if that were the case, Bob would not have blind-played anything.
Furthermore, Cathy knows that Play Clues on 5's one-away-from-chop using rank clues are turned off. Thus, Bob's blind-play must indicate a Chop Move Ignition.
Thus, Cathy's 5 can be any color (including red). Cathy blind-plays her slot 5 card.
Importantly, this interaction is turned off in the End-Game.
Note that sometimes, players will use a rank 5 clue to touch an actual playable 5 that is exactly one-away-from-chop. Regardless of whether or not the 5 is playable, the next player needs to react as if it wasn't playable. (This is because it is agreed that all Play Clue interpretations are turned off.)
The Chop Move Ignition (CMI) (with 2+ cards Chop Moved)
It is also possible to perform a Chop Move Ignition that Chop Moves two or more cards, but this is more complicated.
This kind of Chop Move Ignition is only valid if both of the following conditions are true:
The leftmost Chop Moved card is playable.
The rightmost Chop Moved card is trash or is a copy of an unclued card in the same hand.
For example, in a 4-player game:
All the 1's are played on the stacks.
Cathy's hand is, from newest to oldest: blue 4, blue 1, red 2, blue 4
Alice clues number 1 to Cathy, touching a blue 1 on slot 2.
It is now Bob's turn. Bob sees that Cathy will interpret this as a Trash Chop Move on slot 3 and slot 4.
Bob also knows that it is nonsensical to Chop Move a playable red 2 - Alice could have just give a direct red Play Clue to the red 2.
Thus, this must be a Chop Move Ignition. Bob blind-plays his Finesse Position card. It is blue 2 and it successfully plays.
At first, Cathy thought that Alice's clue was a Trash Chop Move. However, if that was the case, then Bob would not have blind-played anything. Since he blind-played his Finesse Position card, this must be a Chop Move Ignition. Cathy blind-plays her slot 3 card (the card to the right of the clued 1). It is a red 2 and successfully plays.
At the same time that Cathy marked her slot 3 card as playable, she also marked her slot 4 card as known trash.
Later on, Cathy discards her slot 4 card, and discovers that it is a blue 4. Since blue 4 was not trash at the time that the Chop Move Ignition was given, Cathy marks Elimination Notes in her hand for the other copy of the blue 4. (The rest of the team also marks Elimination Notes in the same way.)
If three or more cards are Chop Moved, nothing is promised about the middle cards.
Normally, when a player has a globally known trash card in their hand, they can safely discard it.
In rare cases, a player might decide to intentionally misplay the trash card as a means of communicating a particular slot number as a Positional Misplay. This kind of thing almost always happens on either the last round of the game, or the second to last round of the game.
However, what if a player intentionally misplays a trash card before that point? Wasting a strike for no reason is "useless" in much the same way that the kinds of clues that cause Double Ignition are. Thus, we agree that bombing a card in this way should trigger two blind-plays as a Bomb Double Ignition.
Using a clue instead of using a strike is almost always preferable. Thus, players should prefer to use the more-ordinary forms of Double Ignition (like e.g. Replay Double Ignition) before resorting to a Bomb Double Ignition.
If the team can see that a player who initiated a Bomb Double Ignition could have obviously used a clue-based form of Double Ignition, then this signals an extra message: a Triple Ignition.