The Combo ender is one or multiple unique basic attacks that have a chance (~70%; if successful, all hits will always be performed in the case of multi-hit combo enders) to be possible to perform after a light basic combo. They are performed by swiping once as the arrow shows up. If you swipe in the wrong direction or you don't swipe at all, the combo ender will miss.
Combo enders are significant as they are the only attacks that can apply the different unique effects such as: Power Drain from the Ra's Al Ghul's Scimitar, Life Drain from Gauntlets of Azrael or League of Assassins Adept Blade, and both of the stated status effects from the Overpowered 5-U-93-R. Martian Manhunter/Prime, Green Arrow/Arrow, Darkseid/Apokolips and Green Lantern/Jessica Cruz Rebirth also have their passives affecting combo enders, along with Deadshot, who have a chance to Stun upon their combo enders that is inherent and not part of his passive.
It is impossible for players to perform combo enders on Stunned opponents (the swipe does not show up at all), with the exception of Static, who can use combo enders on opponents stunned by both his SP1 and other characters' stuns. However, AI-controlled characters can use combo enders on stunned opponents. Combo enders can be used on frozen opponents.
By default, there is one combo ender hit and it deals 3% of the character's damage stat as damage, prior to modifications, as opposed to light basic attack's 2% and heavy's 4%. There are plenty of exceptions, however:
- 3% + 3% + 4% + 4% + 4% + 4%: Green Lantern/Jessica Cruz Rebirth
- 3% + 3% + 3% + 3% + 3%: Green Arrow/Rebirth
- 3% + 3% + 3% + 3% (up to + 3% + 4% + 4% additionally with both Batman/Flashpoint and Aquaman/Flashpoint): Deathstroke/Flashpoint
- 3% + 3% + 3%: The Arkham Knight, Harley Quinn/Arkham Knight, Wonder Woman/Dawn of Justice, and Batman/Flashpoint
- 3% + 3% + 2%: Deadshot/Suicide Squad
- 3% + 2% + 3%: The Joker/Batman Ninja
- 4% + 4%: Killer Frost/Prime, Batgirl/Arkham Knight and Ares/The Merciless Metal
- 4% + 3%: all versions of Raven except Raven/Rebirth
- 3% + 3%: Batgirl/Cassandra Cain, Martian Manhunter/Blackest Night, Superman/Blackest Night, Green Lantern/Yellow Lantern Hal Jordan, Scorpion/Klassic, Deadshot/Arkham Origins, Batman/Batman Ninja and all versions of Deathstroke (except Deathstroke/Flashpoint), Nightwing and Hawkgirl (except for Hawkgirl/Earth 2)
- 2% + 2%: Red Lantern Hal Jordan
- 2%: Scorpion/Mortal Kombat X, Martian Manhunter/Prime, Darkseid/Apokolips (further modified by passives)
Darkseid/Apokolips and The Flash/Metahuman are unique in that they can have different amounts of hits in their combo enders. Apokolips Darkseid normally has 1-hit combo enders, but his life steal combo ender hits twice (the normal combo ender, plus the 15% life steal hit). Metahuman Flash's basic attacks hits 3 times with every normal hit during his passive, and thus his normal 1-hit combo ender will also hit 3 times.
Unblocked combo enders will almost always deal a knockdown blow, with the sole exception of Darkseid/Apokolips in Dead Zone. Getting the combo ender is often important to allow you to continue using basic combos on your opponent, as not performing it would often only stagger the opponent very briefly, allowing them to retaliate with their basic attacks before you recover from your own basic combo.
Starting from Darkseid/Prime, the AI can use combo enders with most newer characters. They can use it even if the player is blocking. This can be used against it however; some characters have a long delay between their light combo and their combo ender(s), making it easy to block their light combo then retaliate with your own basics or a special before their combo ender can connect. A prime example is Wonder Woman/Dawn of Justice, who has a powerful combo ender but has an extremely long delay, making it easy to interrupt. On the other hand, while Rebirth Jessica Cruz has one of the strongest combo enders in the game with an extremely long delay, she moves back during that delay so it may be difficult to hit her.
Characters are invulnerable during the swipe of the combo ender (not when actually performing the combo ender). This is noticeable when the opponent with the Enchantress Companion Card EVOLVED just used a special attack, as the skulls will have no effect as long as the swipe is on the screen.
For the purpose of Phantom Zone conditions, no matter how many hits a Combo Ender has, it only counts as 1 Combo Ender per performance (prior to Phantom Zone-specific modifiers).