Reaction
Reactions are an uncommon stat found on a handful of cards. They serve as alternative ways for these cards to trigger besides their 
Counter reaching 0. In many cases, cards with Reactions don't even have Counters at all, and thus can only trigger via the Reaction.
Information and Strategy
Reactions are found on both player and enemy cards. Unlike the usual Counters, a card with a Reaction will trigger immediately whenever some condition is met. A reacting card triggers identically to one triggered by its Counter: it attacks the front enemy in the opposing row and uses its effects (if any). However, some reactions like the Smackback keyword cause the card to trigger against a specific target instead of the front enemy, although it still uses its effects as normal.
Although Smackback is the most common Reaction, it is far from the only one. All Reactions are written in orange ability text to indicate what triggers the Reaction, while any other abilities the card may have are colored normally. For instance, 
Mega Mimik has the orange text "Trigger when an ally in the row attacks," indicating its trigger condition, and "Lose 1 
Scrap" in normal text, indicating that this is an ability unrelated to what causes the Reaction.
Preventing Reactions
The nature of Reactions makes them exceedingly dangerous to offensive Companions, who tend to have low 
health. A card with Smackback is theoretically able to damage any card on the player's field regardless of position, as long as that player card hits it. There are three different ways to prevent a card's Reaction from working, even if the conditions are met:
Snowed cards can never trigger under any circumstances, so this prevents them from triggering by Reactions. A card also cannot react to a hit that inflicts it with Snow; for instance, 
Snoof attacking a 
Spike Wall will not trigger the latter's Smackback.
- Inflicting
Ink on a card negates all its effects, including any abilities it has that would trigger Reactions. If the card has just a Reaction and no Counter, it will never be able to trigger while Inked. Like Snow, the card will also not react to any hit that inflicts it with Ink. For instance, 
Maw Jaw triggers when hit by anything, but it will not trigger when hit by the 
Flask of Ink, since it becomes Inked by the hit that would trigger the Reaction.
- If a card's Reaction has its conditions met but it is killed before its Reaction would trigger, it is removed from the field immediately and will not react. This sets counterattack Reactions apart from
Teeth, which will damage an attacker even if the card with Teeth is killed by the hit.
Reaction Interactions
Counters and Reactions are independent from each other. If a card has both a Counter and a Reaction, the Reaction will not cause the card's Counter to reset when triggering.
If a card with 
Frenzy has a Reaction that causes it to trigger against a specific target (such as Smackback), it will stop attacking if the target is killed in the middle of Frenzy attacks. However, if it also has Barrage or Aimless, it no longer triggers specifically against its target, and instead triggers against the row that the intended target occupies. For instance, a card with Barrage and Smackback will react against its attacker's entire row. This allows the card to use more of its Frenzy in one reaction, even if the intended target is killed partway through. However, if all the enemies in the targeted row are killed partway through the Frenzy attacks, the card will still stop attacking. Uniquely, a card with Longshot triggers appropriately against its Reaction's target (instead of always hitting the furthest enemy), but it can still use more of its Frenzy if the target is killed (in which case it begins hitting the furthest enemy).
Spice and 
Frost are only removed once all attacks are finished and no more Reactions are being triggered. This means that if a card with a Reaction triggered by being hit (such as Smackback or Maw Jaw's Reaction) hits another card with such a Reaction, the cards will repeatedly take turns hitting each other, but their Spice and Frost will only clear once one (or both) of the cards is destroyed. However, if each card is unable to kill the other (such as if they have 0 or less 
attack, perhaps due to Frost), each card's Reaction will only trigger up to two times, to prevent an infinite loop.
A similar form of infinite loop prevention is used for cards with Reactions triggered on an ally's attack, such as 
Mimik and 
Puffball. A card with this type of Reaction cannot trigger other cards with the same type of Reaction; otherwise, having two Mimiks in a row would lead to an infinite number of attacks.
If a card would trigger against multiple targets at once (such as if 
Snoffel inflicts Snow on the enemy field while 
Kobonker is active), the card triggers against each target in reverse turn order, starting from the back of the field and working towards the front. The same is true for if multiple cards' Reactions are triggered at once (such by hitting Smackback cards with a Barrage attack), and the reacting cards will trigger in reverse turn order.
Reactions are separate from activated abilities that also have specific conditions (note the orange text of a Reaction versus the normal white text of a regular ability). These abilities can still activate even if the card is Snowed. For instance, even if 
Grumps is Snowed, it will still lower the attack of whatever hits it. Since Ink negates all a card's abilities, neither a Reaction or an on-hit ability is able to work.
All Reactions trigger in between Frenzy attacks if their conditions are met, which may even kill the attacking card before it finishes all its attacks. When interrupting Frenzy attacks this way, the reacting card uses all of its own Frenzy before the interrupted card continues to attack; for instance, if 
Foxee attacks a 
Warthog that has gained Frenzy via the Wild ability, Foxee will hit the Warthog once, and then the Warthog will react against them with all of its Frenzy (or as much as is needed to kill Foxee).
Checking if a card's 
Overburn should cause it to explode has higher priority than checking its Reaction. If a card would react to something that also causes its health to be lower than its Overburn (whether by inflicting Overburn or damaging it), it will explode before it gets the chance to react. If the card survives its own explosion with 
Shell, 
Block, or Scrap, it will react after the explosion.
Resolving a card's ability or effect is also higher-priority than checking Reactions, so a card will not attempt to react to something until all the effects of the card that triggered it are applied. For instance, if Maw Jaw is hit by the 
Berry Blade, which deals damage and then heals the front ally, Maw Jaw will not react until the ally is healed. Similarly, if 
Monch eats an ally while 
Groff is on the field, Groff will not react until Monch has finished attacking. This property is also what prevents cards from reacting to hits that inflict them with Snow or Ink.
Reactions have a hidden internal order of operations that is not immediately obvious, mainly because some Reactions are triggered on attack declaration, while others are triggered on hit. For instance, assume that a Companion has a Mimik in the row and then attacks an enemy with Smackback. Mimik triggers whenever an ally in the row attacks, while Smackback triggers when the card is hit by another. Because an ally declaring an attack is an earlier event than actually hitting the card, the Companion would attack and hit the enemy card, and then Mimik would trigger and attack before the enemy card could react. If the enemy survived both of these attacks, it would then appropriately trigger against the Companion and Mimik.
Cards and effects that interact with Reactions
| Player cards with Reactions | Player effects that interact with Reactions | Enemy cards with Reactions |
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Other Languages
| Language | Official Name |
|---|---|
| Chinese (Simplified) |
反应 Fǎn yìng |
| Chinese (Traditional) |
反應 Fǎn yīng |
| Korean | 반응 Baneung |
| Japanese | リアクション Riakushon |