Radiance

The Radiance is the secret final boss of Hollow Knight. Absolute Radiance is her perfect form.

Lore
The Radiance is a higher being of light similar to Essence, and as such opposed to the Void, her ancient enemy. The Moth Tribe is born from her light and in return revered her. Unlike the individualist society of Hallownest however, the Radiance offered unity to bugs at the cost of a mind incapable of thought.

After the Pale King arrived in Hallownest and expanded the minds of his new subjects, the Moth Tribe turned their backs on the Radiance and worshipped him instead. In doing so, the Radiance was almost entirely forgotten. Yet traces of her memory remained, such as a statue on Hallownest's Crown. Her memory started spreading throughout the Kingdom, by then in its golden age. Soon, all of Hallownest began to dream of her, appearing to them as a blazing light. These dreams could break the minds of bugs and eventually enslave their wills to hers. But the King and his subjects resisted her memory, which started to manifest as the Infection.

The Pale King attempted to stop the Infection by sealing the Radiance within a Vessel. These creatures, infused with the Void to be without a mind and a will, were to be able to withstand the Radiance's influence. The Hollow Knight was chosen, raised and grown for that purpose. The Radiance was sealed within them, and the Vessel chained within the Temple of the Black Egg. However, the Pale King failed to realise the Vessel's impurities of mind. Because of this, the Radiance was still able to invade the dreams of bugs. She ultimately wiped out the Kingdom of its inhabitants, whose King had vanished, but left the rest of the land untouched.

Time passed, Hallownest turned into a myth while the Radiance remained sealed. Her influence finally started to break out of the Hollow Knight. She reignited the full power of the Infection, threatening again the land of Hallownest and prompting the Knight to return to Hallownest.

Hollow Knight
From her prison, the Radiance senses the return of the Knight and uses the Infection against them. She makes violent puppets out of infected husks, uses Lightseeds and infected Lumaflies to reanimate Broken Vessel and the Watcher Knights, all controlled to kill the Knight. As the Knight draws near to unseal the Black Egg, she increases the spread of the Infection throughout the Forgotten Crossroads to strengthen the creatures infesting it and make them even more violent.

Her fate is linked to the end of the Knight's journey. By defeating the Hollow Knight, the Knight is able to seal the Radiance within, taking the place of their sibling within the Black Egg.

If the Knight enters instead the mind of their sibling with the help of Hornet, they have the possibility to challenge the Radiance herself. However, with the Void unified under the Knight's will,, the battle takes a tragic turn for her. The Void itself slowly creeps in her dream, seeking to ensnare and consume the Radiance. At the end of the fight, it finally catches up with and immobilises her. The Shade of the Hollow Knight takes advantage to expose her core, to which the Knight's own Shade deals the last blows. The Radiance's Essence bursts out as the Void consumes her and vanishes from the Temple of the Black Egg, putting an end to the Infection.

Regardless of Hallownest's recent events, the Godseeker seeks to attune the Radiance to  Godhome, where her people can revere the forgotten being as their God of Gods. The Knight can summon her by defeating the Pure Vessel. With the Godseekers' thoughts focused on her, she becomes the Absolute Radiance, her perfect state. Unbeknownst to the Godseeker however, the Void was also lured within Godhome.

If the Knight pushes through the Pantheon of Hallownest, they can challenge the Radiance in Godhome in a similar fight as within her dream. However as the Radiance is cornered by the Void, the Knight's Shade fuses with it. This time focused on by the Godseekers, they take an all-powerful form and lashes repeatedly at the Radiance's core, her Essence bursting out. She finally shatters, putting an end to her plague on Hallownest.

Phase Breakdown
{{CollapseTable|More...| In general, panic heals are more costly here than in other fights; as SOUL is limited and damage intake is high for mistakes.

Phase 1
There is ample time when The Radiance is spawning, so use this time to hit her with nail attacks or spells. From here, The Radiance will use her attacks one after the other with ample time between, all while hovering above the floor and teleporting. The hardest attacks to avoid are typically the horizontal walls of swords and the homing projectiles. And as the attacks interval shrinks, it is important to be mindful of Shadow Dash cool-down for Wall of Light. With proper timing and spacing, all attacks (save homing spheres) are good opportunities for healing, though the safest options are the third salvo of the eye beam and a break in Spike Wall where the next wave requires no jump to avoid.

Phase 2
The Radiance continues using the same attacks, but will now create spikes across alternating halves of the platform. The restrained space makes it much harder to manoeuvre and to stall out the cooldown of the Shadow Dash. She will switch the location of the spikes every 5 seconds, outlining their new location with a golden glow for about 2 seconds as a warning before they actually emerge. Be sure to use the warning and not panic; take the time to avoid any in-progress attack before moving to safe ground. Keep in mind the spikes can be despawned by entering their hitbox, which can be done without taking damage if utilizing invincibility frames. However, these Spikes only deal one mask of damage, so if forced to take damage between these and other attacks, it is better to hit the spiked ground.

Phase 3
The Radiance will float in the centre of the platform, place spikes at the edges and endlessly rain down swords from above. This is generally not a good time to heal as the spikes come down in fairly short intervals. It is better to get through the phase as there is ample time before phase 3 starts to heal.

Phase 4
The Radiance resumes using all of her normal attacks but is now fought on a field of small platforms over the Void. To the Knight's advantage, they can gain a lot more distance from The Radiance to heal, as all attacks have a lot more ground to cover before reaching The Knight. Wall of Light is an especially good opportunity to heal, as the attack's sound can be heard when it is off-screen, making it easier to know well ahead of time when it is possible to heal. Though when it comes to approaching The Radiance for the offence, several things have to be taken into account: if she is off-screen when she is prepping her next attack, there is limited time to react appropriately, making it more likely to be caught mid-jump by an unexpected attack. In this case, it is much better to maintain distance and wait for the next opening.

Phase 5
The last phase involves ascending by jumping up platforms as The Radiance flees again. Her only attack in this phase is the Big Beam. Upon reaching the Radiance, hit her one more time with the Nail to end the fight and trigger the final sequence.

In the final sequence, The Radiance is bound by Void Tendrils and the shade of the Hollow Knight appears, tearing open a weak point on her face. The Knight bursts out of their body and becomes their Shade. Attacking causes the Shade to repeatedly whip The Radiance's weak point with long tendrils until it's defeated and dragged into the Void below. }}

Charm Sets
The Radiance is the true final boss of Hollow Knight. To access her, the Knight must have acquired Void Heart and have used the Dream Nail on The Hollow Knight when Hornet holds them down. The Radiance does not count as a dream battle, so The Hollow Knight will need to be fought from the beginning on every death.

In the first phase of the fight, she levitates slightly above the floor. Only her body is vulnerable to attack, which requires jumping or ranged attacks. She will often teleport around, making it even harder to get a good string of hits while avoiding her own ruthless attacks.

The Radiance does not deal contact damage; however, all of her attacks except summoning spikes will deal two masks damage upon hit. Falling off the platform will also only do one mask of damage.

Trivia

 * There is a statue of The Radiance at the top of the map in Hallownest's Crown where a Pale Ore can be found. Dream Nailing this statue will yield the lines:


 * "...Remember... Light..."


 * Through HUD manipulation, The Radiance is shown to actually have 3000 health, though the "fight" portion of the battle ends when she reaches 1300 health, effectively requiring the Knight to only have to deal 1700 damage to win the fight.


 * Along with Nightmare King Grimm, The Radiance is one of the only bosses that has a fullscreen title card.


 * The Radiance is confirmed to be female through translations of the game, as well as from developer notes regarding the Seer:


 * The moth tribe were (perhaps) descended from Radiance. However, the King convinced them somehow to seal Radiance away. I guess so he could rule Hallownest with his singular vision, as a monarch/god with no other gods. The moths sealed Radiance away by forgetting about her. Hallownest was born and flourished. However, the memory of Radiance lingered (eg the statue at Hallownest's crown) and soon she began to reappear in dreams and starting exerting influence. The King and the bugs of Hallownest resisted this memory/power and it started to manifest as the infection. Thus the first attempt to seal Radiance failed, and the King had to try another method - the Vessel.


 * The Radiance is one of the two bosses, excluding statues in the Hall of Gods, that must be challenged to a battle, the other being the Mantis Lords. While the Mantis Lords will have to be challenged every time, the Radiance's intro is abridged after the first time fighting it, causing her to attack directly upon entering her arena.


 * The Radiance fight is one of four fights in the game where an NPC aids the Knight; the other three are Traitor Lord with Cloth, The Hollow Knight with Hornet and Uumuu with the aid of Quirrel.


 * The Design of The Radiance appears to be based on a Silkworm Moth.


 * The Radiance being called "Light" could be a reference to real moths, as they are attracted to light sources.