Counter

Counter is one of the first moves taught in the Arkham games (the other being Strike). It is performed by pressing the counter button (by default, X on Xbox, triangle on PlayStation, and right mouse button on PC) in response to an incoming attack. It is a defensive, passive attack and it can only be performed successfully in response to an incoming attack but if not done correctly during a combo (e.g., poorly timed), the player will be hit and the Combo will be broken.

Practicality
The counter is a basic and important attack. It is easy to perform, and if well-timed, it can help players to counter any counterable attack successfully without harm. Due to the nature of the Combat Variation system of the Arkham games, spamming the normal strike too quickly can leave players vulnerable, which is why a counter here and there is very useful to avoid getting hit due to such a poor combat rhythm. Non-counter attacks with Batman (the slowest character) may easily fail against quick enemies such as Ninjas or Combat Experts if they're about to launch counterable attacks and result in him getting hit, therefore using counters against these attacks is preferable.

A counter adds 1 multiplier to the combo meter, then 10 points for each multiplier, just like a normal strike. It also adds 1 combat variation. Like strikes, Freeflow Counters can knock over enemies. However, a counter against an Armored Henchman or a Brute does not add any multiplier, and does not knock them over. If an enemy is all alone or the last standing one, a counter will immediately finish them. In Arkham Knight, a counter can also finish up to 3 last standing enemies, unlike in previous games where it only grounds them.

In Arkham Asylum, only one enemy can be countered at a given time, and the character has to be rather close to the attacking enemy. In Arkham City and later games, up to three enemies can be countered simultaneously (which adds up to three multipliers at once), and the counters are much more powerful that they can blast a henchman onto another, while also having a wider range.

Counters are usually used in combat situations. However, in Arkham City  onwards, during Predator Mode, counters can be used against henchmen who are unable to use their guns for whatever reason, and can quickly take out even Armored Henchmen.

Counter Icons
Due to its importance, an icon in the shape of lightning bolts appears around the head of an enemy to signal the counterability of their incoming attack. In Asylum, counter icons are disabled in hard mode; in City and later games, counter icons are only disabled in New Game + mode and Origins's I Am the Night mode.

A counterable attack is signaled by a blue counter icon: it can easily be countered by pressing the counter button. These attacks include punches, kicks, hits with blunt Weapons or projectiles, and blade attacks swung from above by ninjas and Combat Experts.

An uncounterable blade attack is signaled by a yellow counter icon: it cannot be countered (therefore, adds no combat variation), and can only be dealt with by an evasion, a Blade Dodge, or a Blade Dodge Takedown. These attacks include blade attacks from henchmen, and blade attacks swung from below by ninjas and combat experts.

Other uncounterable attacks are signaled by red counter icons: they cannot be countered in any way and has to be dealt with by various ways. They include electricity-based attacks (using Stun Batons, shock gauntlets, or Electric Currents), shield attacks, gunfire, and attacks by large bosses such as Albert King and Killer Croc, and some attacks by Bane, too. In Arkham Asylum, projectiles and blade attacks were marked with red icons because they were not counterable; in later games, projectiles became counterable, while blade attacks could be dealt with with the Blade Dodge Takedown mentioned above.

Variants
In Arkham Origins, there's an upgrade called Critical Counter that can only be performed when the enemies' attacks are very close to hitting. A Critical Counter adds 2 multipliers at once and more damage. As its name suggests, a Critical Counter is similar to a Critical Strike, and can only be done during Freeflow.

In Arkham Knight, the Critical Counter is replaced by the Throw Counter. It is performed in a similar way, but now the character has to also move toward the attacking enemies and the move is also green lit by a brighter counter icon. It is only available for Batman, Azrael and Batgirl. By performing a Throw Counter, the character will throw, punch or kick up to two enemies farther away, hitting other enemies in the way. Batgirl can't throw enemies very far and can only do so on one enemy at a time; Batman and Azrael, however, can Throw Counter up to 2 enemies at once and blast them very far away. A Throw Counter also adds 2 multipliers at once. It doesn't have to be done during Freeflow. Animations for Throw Counters take a bit more time than those for regular counters. The Throw Counter is not an upgrade, but still it can only be acquired after a tutorial AR challenge that shows you how to do it, if you're on a new run (not a New Game + run). The tutorial is available immediately after you've been equipped with the Batsuit Version 8.03.