The Cosmic Pulse

Warlocks of the Cosmic Pulse forge pacts not with fiends or fey, but with the remnants of dying stars. These patrons are the collapsed hearts of suns, fragments of radiant titans whose last breath echoes across eternity. To their chosen, they offer rhythm and resonance: the power to turn the cadence of a heartbeat into a weapon.

Such warlocks are conduits of collapse. Their spells crackle with stellar resonance, their bodies hum with unearthly vibration, and their eyes flicker like fading suns. Whether they believe their patron to be a single ancient star, the echo of a cosmic choir, or the pulse of the universe itself, these warlocks walk with the weight of stellar death behind every step.

Eldritch Blast can be reflavoured to "Pulse of the Void" in order to fit this theme:
"You unleash a resonant wave of void energy, an echo of a dying star’s heartbeat."

Preface

The Cosmic Pulse is a subclass built around rhythm, resonance, and volatility. Before diving in, here are some assumptions and intentions to set expectations.

Balancing Context

This subclass assumes MCDM’s Flee, Mortals! pacing (2–3 challenging encounters per long rest, with a short rest in between). It thrives when combat encounters are dynamic set pieces rather than attritional grinds.

If you play by the traditional 5e adventuring day (6–8 medium encounters, 2 short rests, 1 long rest), the Cosmic Pulse may feel overtuned. In the intended pacing, it sits beside other official and homebrew subclasses as a balanced, if swingy, option.

Target Audience

The Cosmic Pulse is for players who love:

- Building combat loops that reward momentum instead of spamming the same cantrip.
- Managing resources turn-by-turn with Resonance stacks.
- Swingy, high-dopamine mechanics like Surge Rolls.
- Complex, tactical play with no single “correct” answer.

If you want a plug-and-play subclass with low bookkeeping, this is not it. But if you thrive on timing bursts, weighing risk against reward, and having no turn be like the last, you’re in the right place.

Playtesting

This is an early release with rough first-pass numbers. Feedback is welcome, especially from tables that push subclasses to their limits.

Level 3: Resonance

Your body vibrates with the rhythm of the Cosmic Pulse, measured in Resonance, the unstable echoes of a collapsing star.

• Gaining Resonance: When you cast Eldritch Blast and at least one beam hits a creature, you gain 1 Resonance (regardless of how many beams hit).
• Empowered Eldritch Blast: When you cast Eldritch Blast and at least one beam hits a creature, you can deal an additional 1d4 force damage per Resonance to one of the creatures hit by that casting.
• Empowered Magic Missiles: When you cast Magic Missiles at maximum Resonance, you can add an additional 1d4 force damage per Resonance to one target of that spell. This additional damage may be blocked by the Shield spell.
• Maximum Resonance: You start with a maximum Resonance of 4. This raises to a maximum of 6 at 9th-level, 8 at 14th-level, and a maximum of 12 at 20th-level.
• Duration: Your Resonance stacks remain for 1 minute. This duration is refreshed each time a stack is gained.

Level 3: Resonant Backlash

The Void’s heartbeat grows unstable at high resonance.

Whenever you cast Eldritch Blast at maximum Resonance, roll a d20 after resolving the attack. On a roll of 1, you take force damage equal to the extra damage dice added by Resonance (Xd4), losing all of your Resonance stacks.

Resonant Backlash. The default option, as described above.

Scaling Resonant Backlash (Optional). Each additional cast at maximum Resonance increases your backlash range by 1 (so the second cast fails on 1–2, the third on 1–3, etc.). This resets once you fall below max resonance. 

Resonant Backlash

The Void’s heartbeat grows unstable at high resonance.

Whenever you cast Eldritch Blast at maximum Resonance, roll a d20 after resolving the attack. On a roll of 1, you take force damage equal to the extra damage dice added by Resonance (Xd4), losing all of your Resonance stacks.

Scaling Resonant Backlash

The Void’s heartbeat grows unstable at high resonance.

Whenever you cast Eldritch Blast at maximum Resonance, roll a d20 after resolving the attack. On a roll of 1, you take force damage equal to the extra damage dice added by Resonance (Xd4), losing all of your Resonance stacks.

Each additional cast at maximum Resonance increases your backlash range by 1 (so the second cast fails on 1–2, the third on 1–3, etc.). This resets once you fall below max resonance.

Level 3: Cosmic Pulse Spells

The magic of your patron ensures you always have certain spells ready; when you reach a Warlock level specified in the Cosmic Pulse Spells table, you thereafter always have the listed spells prepared.

Fiend Spells

Warlock Level	Spells
3	Magic Missile, Shield, Faerie Fire, Mirror Image, Misty Step
5	Counterspell, Fly
7	Greater Invisibility, Dimension Door
9	Wall of Force, Scrying

Level 3: Surge Rolls

Some features call for a Surge Roll, representing how closely your will aligns with the cosmos in a pivotal instant.

Matching Surge Roll. Both you and the GM roll a Surge die. If the numbers match exactly, a Surge occurs and the feature’s bonus effect triggers. Otherwise, nothing happens, or

Surge Roll Max. You roll a Surge die. If you hit the maximum value, a Surge occurs and the feature’s bonus effect triggers. Otherwise, nothing happens.

Matching Surge Roll

Some features call for a Surge Roll, representing how closely your will aligns with the cosmos in a pivotal instant.

Both you and the GM roll a Surge die. If the numbers match exactly, a Surge occurs and the feature’s bonus effect triggers. Otherwise, nothing happens.

Critical Auto-Success. If you score a critical hit with an attack that calls for a Surge Roll, that Surge automatically succeeds (no roll required). Critical hits with other attacks that do not involve a Surge Roll have no additional effect.

Surge die:

• Levels 1–10: Surge Rolls use a d8 (12.5% match chance).
• Levels 11–16: Surge Rolls use a d6 (16.7% match chance).
• Levels 17–20: Surge Rolls use a d4 (25% match chance).

Surge Roll Max

Some features call for a Surge Roll, representing how closely your will aligns with the cosmos in a pivotal instant.

You roll a Surge die. If you hit the maximum value, a Surge occurs and the feature’s bonus effect triggers. Otherwise, nothing happens.

Critical Auto-Success. If you score a critical hit with an attack that calls for a Surge Roll, that Surge automatically succeeds (no roll required). Critical hits with other attacks that do not involve a Surge Roll have no additional effect.

Surge die:

• Levels 1–10: Surge Rolls use a d8 (12.5% match chance).
• Levels 11–16: Surge Rolls use a d6 (16.7% match chance).
• Levels 17–20: Surge Rolls use a d4 (25% match chance).

Level 3: Resonant Cascade

Your gathered energy bursts outward in a wave of starlight, motes of collapsed suns tearing through the battlefield.

Expel all Resonance in a 20 foot radius centered on a point within 120 feet, using up all Resonance stacks. All creatures in the radius must make a Dexterity saving throw against your spell save DC.On a failed save, a creature takes Xd8 Force damage, where X = Resonance spent; half as much on a success.

Surge Roll. If a Surge triggers, it unleashes a Cosmic Flare that erupts outward from you (see Cosmic Flare below). This eruption does not count against your normal uses of Cosmic Flare, and it can occur even if you have not yet unlocked that feature.

Level 6: Gravitational Collapse

The space around your foe twists and folds, dragging nearby matter into its imploding core.

While at maximum Resonance, the added Resonance damage, as per the Resonance feature, is dealt to all creatures within a 5 foot radius of that target.

Level 6: Cosmic Flare

You hurl a burning streak of stellar plasma, a miniature flare carved from the void.

A Cosmic Flare releases from you in a 30 foot line, 5 feet wide. All creatures in the line must make a Dexterity saving throw against your spell save DC. On a failed save, a creature takes 4d6 force damage; half as much on a success. You gain 1 Resonance for each creature hit. This attack’s damage increases by 2d6 when you reach 14th level (6d6), and 18th level (8d6). This can be used two times per long rest. You can regain one use of this feature by expending a Pact slot.

Level 10: Cosmic Harmony

Your rhythm steadies; your heartbeat aligns with the cosmic drum, protecting you as you stride through battle.

At the start of your turn, if you have 2 or more Resonance, you gain temporary hit points equal to your Charisma modifier.

While at maximum Resonance, your movement speed increases by 10 feet and you ignore difficult terrain. 

Level 14: Resonant Mastery

You have learned to ride the storm of resonance, no longer fearing its backlash but bending it to your will.

You are immune to Resonant Backlash damage, though you may still lose your Resonance.

When you gain Resonance, you may instead choose to immediately expend it. For each point gained this way, deal 1d4 force damage to one creature you can see within 30 feet.