In 'The King of Fighters AFK' (hereinafter 'KOF AFK'), fighters possess 'Synergy' effects. The mechanic is simple: slotting two or three fighters with matching synergies into your party activates the boost. Note that Orochi Iori and Orochi Leona wield 'Special' synergies that trigger even when fielding only one of them. These effects unlock from stage 351, and since they can drastically bolster your party's combat prowess, it is wise to study them early. KookminTree has compiled the definitive guide to KOF AFK synergy effects and recommended fighters.

Attack-oriented Synergies: Fury, Erosion, Execution, and Surge

Fury pumps up the damage of your 'Finish Skills'. A 2-fighter setup grants a 100% boost, which climbs to 120% with 3 fighters. Among the offensive synergies, this is easily the most versatile. Top picks include Chizuru, Maxima, Shen, Meitenkun, and Kensou. Chizuru boasts a 2-turn cooldown evasion, while Maxima gains 10 PG upon being hit and packs a stun for two enemies. Shen shreds a single target's defense by 40% and features a passive that stacks Finish Skill damage up to three times, pairing perfectly with this synergy.

Meitenkun puts two enemies to sleep, rendering them 'incapacitated and untargetable for skills'. This effect breaks upon taking damage, allowing you to effectively stall enemy turn patterns. Kensou's passive adds 5% Finish Skill damage per enemy, stacking to 15%. Just be aware that its efficiency drops when facing a lone dungeon boss.

Erosion is the go-to for those stacking damage-over-time (DoT) and supplementary damage. Like Fury, it scales to 100% and 120% based on party size. If your roster relies on persistent attrition, this is your synergy. Recommended fighters: Joe, Benimaru, Mr. Big, Saisyu, Billy, and Krauser.

Joe applies 'Laceration' for turn-based damage, while Benimaru and Mr. Big favor 'Electrocution'. Saisyu and Billy bring the 'Burn', and Krauser inflicts 'Frostbite'. These fighters all excel at stacking debuffs, making them a natural fit.

Execution focuses on snowballing; you gain increased damage for your next attack upon defeating an enemy. This provides a 75% to 90% damage boost, which is instrumental for clearing stages quickly. Recommended fighters: KUSANAGI, Lee Jinju, Isla, and Ryo.

KUSANAGI strikes all enemies in the target's row and, via a passive, sacrifices some HP to deal 50% bonus damage. Lee Jinju reduces skill cooldowns by 50% after a kill and applies a 60% critical damage resistance reduction debuff to the target. While all skills are single-target, the passive allows for rapid-fire active skill usage.

Isla recovers 100% of her PG if she secures a kill with a Finish Skill, effectively allowing for back-to-back finishers. Combined with the Execution synergy, the damage output is massive. Ryo increases his attack power by up to 20% in proportion to his missing HP and restores 5% HP upon downing an enemy.

Surge boosts damage for normal and active skills. Because these are used frequently, the coefficients are lower, at 50% and 60% respectively. Recommended fighters: Shun'ei and Jeon Hoon.

Shun'ei's passive triggers a normal skill whenever an active skill lands. Jeon Hoon simply uses an active skill twice. They are the prime candidates to fully leverage Surge's damage buffs. Pairing this with Erosion can further amplify the extra attack damage.

Defense-oriented Synergies: Endurance, Wedge, and Solidarity

Endurance boosts the defense and HP of your entire team. A 2-fighter setup grants 10% defense and 15% HP, while 3 fighters bump this to 20% and 25%. Recommended fighters: Tung Fu Rue and King.

Tung Fu Rue grants a 2-turn barrier to the whole team via an active skill, with damage absorption capped at 15% of max HP. With a passive that boosts HP when placed in the front row, plus the Endurance synergy, Tung Fu Rue's effective HP can soar by 35% to 45%. King increases her own agility to secure turns faster, allowing her to trigger active skills early and provide a critical damage buff to allies in the same row.

Wedge increases HP by 15-25% and boosts penetration—which lowers enemy defense—by 10-20%. It is a solid choice for balancing sustainability and damage. Recommended fighters are Shermie and Yuri. Shermie utilizes 'grapple' skills that hit every enemy except for certain massive bosses, ensuring the penetration bonus lands. Yuri boosts the attack and agility of allies in her row to seize the initiative, and since her active is also a grapple-type, she enjoys the same benefits as Shermie.

Solidarity focuses on critical damage resistance and HP. Since it specifically mitigates critical hits, it is best utilized in PvP. Depending on the setup, critical damage resistance increases by 20-40% and HP by 15-25%. Recommended fighters are Clark and Ralf. Clark grants a 40% defense buff to allies in his row and gains 20% HP when placed in the front, cementing his role as a sturdy tank. His grapple-based active and finisher provide guaranteed damage to boot.

Ralf acts as the opposite of Clark, providing a 40% attack buff to his row. His passive also grants him extra HP. Note, however, that unlike Clark, only Ralf's active is a grapple; his finisher is a strike-type, so it can occasionally miss.

Orochi-exclusive Special Type

The final category is the Special type, currently limited to Orochi characters. Though bundled as 'Special', there are two distinct effects. Crucially, you can only slot one of them in your party, as their effects do not stack. There are also 'Acquisition Effects': Orochi Iori boosts the entire team's HP by 100%, and Orochi Leona boosts attack power by 100%.

Orochi Iori's 'Madness' increases his damage dealt by 75%, boosts other allies' attack and HP by 15% while he is alive, and reduces cooldowns for both himself and his team whenever anyone lands an attack. In short, he is a cooldown-reduction engine, allowing for more frequent active skill usage.

Orochi Leona's synergy is 'Frenzy'. Its main benefit is PG generation for herself and her team, with a charge value of 30 under the same conditions as Orochi Iori. She also shares the same 75% damage boost and team-wide attack/HP buffs.

As mentioned, Special synergy does not apply if both are fielded together. You must choose based on your party's core strategy. Orochi Iori pairs beautifully with Surge for cooldown-heavy rotations, while Orochi Leona’s constant PG charging makes her the perfect partner for Fury, allowing for continuous, devastating Finish Skill usage.