The Dark Inferno is a large, muscular, humanoid figure with a large, heart-shaped hole in its chest. It bears a striking resemblance to the Invisible Heartless. Raised portions and ridges on its black skin give it an armored appearance. It features large, spiked horns on the sides of its head, and two more rising from its forehead which form the shape of a heart; all four horns fade from black to red to yellow, giving them the appearance of heated metal. Its tail ends in a bladed fin with a diamond-shaped hole through it. Its two-toed, clawed feet stand upon swirling vortexes of white energy, which it uses to "skate" around the battlefield. It has undersized, purple bat-like wings on its shoulders and dull purple tendrils wrapped around its throat like a scarf, which drape down on either side of its "heart." It also has tendrils wrapped around each wrist, which fade to the same burning yellow color as its horns. In each hand it holds a large blue sword with hook-like extensions near the tip and an exaggerated gold hilt with a knuckle bow.
Its name refers to its association with darkness, sharing a naming scheme with many other Pureblood Heartless, and the burning appearance of its horns and tendrils, along with its fiery attacks.
The battle will begin after accessing the 14th Battlegate in the Keyblade Graveyard. The battle starts with Sora and Dark Inferno equidistant from each other. As the battle starts, Dark Inferno jump further back and begin with one of two attacks: either the Dark Inferno will perform a long combo at Sora which can be blocked, after which the Dark Inferno will attack with a red drilling move that cannot be blocked, or the boss will fly at Sora and perform a two-hit combo and following with a cross slash. If Sora blocks the latter move, performing a reprisal will stun the boss and leave it open for attack. The Dark Inferno can be attacked with nearly two full combos, but it is recommended that Sora stops his second combo before the boss blocks with its swords. Striking Dark Inferno again while it is blocking will result in Sora's attack getting knocked back and the Dark Inferno countering.
Usually, the boss will constantly stay out of melee range which may tempt the player to use magic. The Dark Inferno has a few other attacks Sora must watch out for: One has the boss position itself on the ground and then cause its swords to glow. The boss will send a red wave of energy around itself which will stun Sora if the attack is not avoided. If Sora is further away, one option is to use Airstepping to close the gap and immediately attack. The other attack has the boss combine its swords, impale them into the ground, and spawning a dark pool. Dark Inferno will spawn several white orbs and then disappear into the ground, sending the orbs to track and surround Sora. It is possible to attack Dark Inferno and interrupt the attack, but it is not recommended. Avoid the orbs by jumping over them and using Doubleflight to gain more height, and then glide around the battlefield, as the orbs will not be able to hit Sora as long as he's moving. After the orbs have vanished, Dark Inferno will return and continue to cycle through its attacks.
After five health bars of the boss's health remain, Dark Inferno will cross its swords over himself quickly and it will start to glow purple. Unlike other hidden bosses, Dark Inferno will not add new attacks as its health gets lower, but simply compile its attacks on top of each other, and perform them more sporadically. Its red wave attack now has increased range.
After eleven health bars of the boss's health remains, Dark Inferno will begin to glow red. This is its last phase, but also its most deadly. Note that in this phase, Dark Inferno is immune to Fire-type attacks. Dark Inferno will now begin to relentlessly combo Sora. It will start with its long combo, then quickly change to its two-hit attack, and then perform its long combo again, finishing with its drilling attack. Second Chance and Withstand Combo are critical to this phase of the fight to survive its attacks. Dark Inferno will now disappear during its dark orb attack, will perform its red wave attack with increased range, or will chase after Sora and try to use its two-hit attack. If Dark Inferno chases Sora, block the attack in mid-air, then perform a reprisal. The counter should end with enough time for Sora to Air Dash and start gliding again.
As the Dark Inferno jumps out of attack range to prepare for its next attack, Sora can get in some damage with the usage of a Shotlock command.
Notes and references