This page is about a Mod, and is not part of official Hollow Knight or Silksong content.

A mod that turns the Nightmare King Grimm fight into a custom duo boss with the Pure Vessel.

Nightmare & Void is a Mod for Hollow Knight, which adds a boss of the same name.

Boss

Twin gods of mayhem

– Hall of Gods statue

Nightmare and Void are a dual boss added to Hollow Knight by a Mod of the same name. It adds Pure Vessel in the fight against Nightmare King Grimm, and synchronises their attacks.

Behaviour and Tactics

This boss uses attacks from Nightmare King Grimm and Pure Vessel. They attack in tandem, with predefined pairs of moves determined by the phase. A phase change occurs every Pufferfish attack from Grimm (75%/50%/25% of his health).

For details on the original attacks, see Nightmare King Grimm § Behaviour and Tactics or Pure Vessel § Behaviour and Tactics.

Phase 1

Duo Spikes – Cloak Spikes and Soul Pillars: After Nightmare King Grimm's Cloak Spikes attack, Pure Vessel teleports above the Knight and performs a Soul Pillars attack. This repeats for a total of three times in a row.
Duo Shots – Fire Bats and Soul Daggers: Nightmare King Grimm and Pure Vessel teleport to position themselves on opposite edges of the arena and perform a Fire Bats attack and a Soul Daggers attack, respectively.
Dive Slash – Dive Dash and Triple Slash/Lunge: Pure Vessel teleports beside the Knight and begins a Triple Slash or a Lunge attack. Shortly after, Nightmare King Grimm teleports in the air and begins a Dive Dash attack.
Pillar Dash – Flame Pillars and Triple Slash/Lunge: Nightmare King Grimm begins a Flame Pillars attack as Pure Vessel teleports beside the Knight and performs a Triple Slash or a Lunge attack.

Pufferfish (75%)

As Nightmare King Grimm does the first Pufferfish attack, Pure Vessel's Soul Daggers begin to fall vertically on each side of the arena. The daggers' paths are telegraphed with a soft white line.

Phase 2

Duo Spikes: See Phase 1
Duo Shots: See Phase 1
Dive Slash: See Phase 1
Pillar Focus – Flame Pillars and Focus: Pure Vessel begins performing a Focus attack as Nightmare King Grimm begins a Flame Pillars attack. The main focus aura bursts near the end of the first Flame Pillar. There are no secondary focus auras.

Pufferfish (50%)

As Nightmare King Grimm does the second Pufferfish attack, Pure Vessel's Soul Pillars slowly appear at the Knight's position. Each pillar telegraphs as the previous pillar appears, and appears after the previous pillar disappears.

Phase 3

Duo Spikes: See Phase 1
Duo Shots: See Phase 1
Dive Slash: See Phase 1
Pillar Focus: See Phase 2
Slash Shot – Dash Uppercut and Soul Daggers: Nightmare King Grimm begins the Dash Uppercut as Pure Vessel fires the first of the Soul Daggers.
Slash Feint – Dash Uppercut and Triple Slash: Pure Vessel readies for a Triple Slash attack, but teleports away as Nightmare King Grimm appears near the Knight and performs the uppercut half of a Dash Uppercut.
Lunge Uppercut – Dash Uppercut and Lunge: Pure Vessel starts performing a Lunge attack, and teleports away as Nightmare King Grimm appears near the Knight and performs the uppercut half of a Dash Uppercut.

Pufferfish (25%)

As Nightmare King Grimm does the third Pufferfish attack, Pure Vessel performs a series of Lunge and Triple Slash attacks.

Phase 4

Duo Spikes: See Phase 1
Duo Shots: See Phase 1
Dive Slash: See Phase 1
Pillar Focus: See Phase 2
Slash Shot: See Phase 3
Slash Feint: See Phase 3
Lunge Uppercut: See Phase 3
Tendril Spikes – Cloak Spikes, Void Tendrils and Soul Pillars: Pure Vessel performs a Void Tendrils attack which begins when Nightmare King Grimm's Cloak Spikes disappear. After the attack, Pure Vessel teleports above the Knight and performs a single Soul Pillars attack.
Slash Spikes – Cloak Spikes, Triple Slash/Lunge and Soul Pillars: Pure Vessel performs a Triple Slash or a Lunge attack at the same time as Nightmare King Grimm's Cloak Spikes. After the attack, Pure Vessel teleports above the Knight and performs a single Soul Pillars attack.

Stagger Values
Description: Identical to Nightmare King Grimm's stagger. Pure Vessel does not activate during the stagger.
Hits: 14
Combo: 12	Combo Time: <1s per hit

Variations

Nightmare and Void Hall of Gods text: Twin gods of mayhem
Pantheon	N/A
Health
		1600

Arena changes	No changes

Location

Replaces the Nightmare King in the Hall of Gods.

Gallery

Trivia

All instances of Pure Vessel's Triple Slash and Lunge are the same attack in the code. Due to Pure Vessel's own mechanics the boss alternates between them sometimes.
- Likewise, the Slash Spikes attack is the same as the Tendril Spikes attack in the code. Pure Vessel changes the attack used from Void Tendrils to Triple Slash/Lunge when certain conditions are met, such as the positioning of the boss.

Mod:Nightmare & Void

Boss