Freeflow Combat is the smooth and adaptive structure of fighting in the Arkham Series.
After starting a fight, reaching a two-multiplier combo (shown in the upper left corner), the character enters Freeflow Combat at the third multiplier (added by either a strike or a batarang and signaled by slow motion and sound effects). This is why there are some ways for you to immediately initiate Freeflow by simultaneously adding two multipliers, typically running to get momentum then striking or slide tripping, rather than just striking or countering twice. Some heavy attacks also adds 2 multipliers if used to initiate Freeflow, unlike normally when they only adds 1 multiplier during Freeflow, such as the Batclaw Slam or the Aerial Attack; or in the story mode or predator situations, also the glide kick, the glide boost attack and the pounce attack. A starting, non-Freeflow Blade Dodge Takedown adds only two multipliers to initiate Freeflow rather than three like a Freeflow one. As long as the combo is kept, the character can attack further distances, more enemies and gains more speed. However, failing to counter, hitting air or a shielded enemy or not doing anything for longer than about 1 second instantly ends the combo.
While the combo counter only increases by 1 multiplier per strike, each game allows upgrading to Critical Strikes, which increases the combo by two, provided that the player do not mashing the strike buttons continuously. Even though the on-screen instructions say timing is required for a Critical Strike, it is merely to train players not to frantically strike but to take it slow, because you can still do a Critical Strike even if you've evaded so many times after the last strike.
Once the counter turned yellow (at the initial eighth, or after upgrading, fifth multiplier), the player could perform a special move, which served different functions: one could instantly take any normal enemy out, others would temporarily stun nearby opponents, and one could even destroy their weaponry. After such a move is used, the yellow "special move" meter expires until eight or five more multipliers are added.
Most of the aforementioned features of Freeflow Combat are only available in combat situations. In predator situations, players can initiate Freeflow similarly and use some similar attacks such as normal strikes and counters (which are much more powerful for taking down enemies quickly), Beatdowns, etc., but cannot use Critical Strikes or Special Combo moves.
Batman: Arkham Asylum
Compared to the later entries in the series, the original game's combat was quite simplistic. Batman could punch, counter, stun and leap over his opponents, and eventually use both the Batclaw and Batarangs as weapons. Ground Takedown, while difficult to perform, awarded the most points if used. Special Combo moves were not initially available, and were upgrades the player could buy.
Batman: Arkham City
The combat system was greatly improved upon, and Batman gained several new moves to use against his opponents. Batman could now use more gadgets in combat, had access to more special moves, and could weaponize the stun move, by using it to initiate a Beatdown or an aerial assault; alternately, he could now knock enemies down (but not out) by swinging his cape at them until they lost balance.
Once he "Freeflow Focus" was purchased, he would begin to experience his surroundings in slow motion once he reached a 12 hit combo without using any special moves. This focus would however be lost if he used any special move during it. An another upgrade, Freeflow Focus Gadgets, allowed him to end the focus mode with the benefit of increasing the power of his quickfire gadgets; this upgrade could not be turned off, however, and only affected Batman. If used in Freeflow Focus Mode, usable gadgets become much more powerful: 3 powerful Batarangs can be thrown instead of one and they keep enemies down for longer; the Batclaw Slam is much more powerful and it generates a blast that pushes nearby enemies away a bit; Explosive Gel has much wider blast range and enemies are down for longer as a result; the REC shocks many enemies instead of just one; the Freeze Blast freezes many enemies instead of just one.
Batman: Arkham Origins
The combat remained largely the same as in City, but Batman had a different set of quickfire gadgets, and could upgrade his focus to last until he used two special moves. He would later gain access to the Shock Gloves. The Shock Gloves are arguably overpowering as it allows Batman to get 2 multipliers for a strike, 3 for a Critical Strike, and it can pierce through all enemy defenses.
Batman: Arkham Knight
While the system remained mostly the same, several new additions and changes are present. New additions include the ability to strike downed enemies, and picking up downed enemies to finish them up quicker. Additionally, using the aforementioned pickup immediately after knocking out an enemy would cause the character to throw them over their head, adding insult to injury and preventing the player from losing their combo if they didn't notice the knockout. Several changes, however, were present.
The slow motion effect of Freeflow focus was removed. Instead, the characters gain more attack power when it's activated, and it's now tied to the Special Combo meter; It will be activated upon reaching a combo of 5/8 hits. Freeflow focus gadgets could now be used as any character (But not with every gadget; Batman also had to own the same or a similar gadget, such as Explosive Gel and Shuriken/Batarang.), and were activated by holding the quickfire button, allowing the player to use gadgets normally during focus.
After Batman gains access to the Batsuit 8.03, the increased mobility of the suit allows him to use his attacker's momentum against them. By timing the counter and holding the movement control when the counter icon sparks brighter as the enemy is just about to hit Batman, he should throw the attacker to the desired direction. This can knock down any enemies on the path.
The Batswarm move was removed. The same controls now allow certain characters to pick up enemy weapons left on the ground and use them for extra damage and the ability to bypass thug defenses. However, these weapons will break after a few uses.
Additionally, the game introduces Enviromental Takedowns. Certain objects in the surroundings will be highlighted with blue, and getting an enemy close enough allows the character to instantly take them out by using the object.
However, Batman wasn't the only one who learned more moves. Gotham City's thugs also know a few more tricks than before. Even normal thugs could now charge at the character, who in turn could either evade over them or use their primary gadget for a instant knockout. Additionally, they could now grab the character from behind, allowing other enemies to get in a few punches unless they escaped quickly.
In addition, in several parts of the game, players could perform Dual-Play Takedowns, which instantly took out an enemy. They consisted of both playable characters focusing their attacks on a single enemy, and taking them out quickly and effectively. They could only be done in special circumstances where both characters were fighting together, such as when Batman and Nightwing took down Penguin's weapon caches. A wheel in the corner of the screen charged as you hit enemies, and once full, allowed the player to perform the combo. That wheel also appeared on Free Roam if Batman was fighting near the Batmobile, and when full, allowed him perform an Environmental Takedown with the Riot Suppressor Cannon of the Batmobile.