The Atom

In battle, theres only two outcomes. You either win or you die, the difference is how hard you're willing to blow the other sum***** up until they use their name as a replacement for warcrime.
- Kallahan

Warlocks who enter into a pact with the entity known as The Atom tap into the primal forces of nuclear energy and atomic power. The Atom is a mysterious and ancient force, embodying both the fundamental building blocks of the universe and the unimaginable devastation that can be unleashed when these forces are unleashed. Warlocks of The Atom wield explosive magic with the precision and intensity of a nuclear reaction, bringing both creation and annihilation to the battlefield.

Expanded Spell List

1st level feature

The Atom lets you choose from an expanded list of spells when you learn a warlock spell. The following spells are added to the warlock spell list for you.

1st level - Thunderwave, Catapult
3rd level - Cloud of Daggers, Flaming Sphere
5th level - Fireball, Conjure Animals
7th level - Gravity Sinkhole, Resilient Sphere
9th level - Destructive Wave, Antilife Shell

17th level (Mystic Arcanum) - Meteor Swarm

Helter-Skelter

1st level feature

You begin to harness the power of the Atom, a mysterious building block of matter that gives off explosive energy when split. When you cast a cantrip or spell that deals Force or Fire damage, you can change the damage type to Radiant instead.

Additionally, you create small pockets of explosions when you hit with your spells. When you hit a creature with an attack roll, you can create an explosion of 5 ft. radius that affects creatures of your choice and forces them to make a Dexterity saving throw against your spell save DC, dealing radiant damage equal to your Warlock Level + your Charisma modifier and half as much on a success.

Nuclear Cascade

6th level feature

The secret to Atomic explosions is chain reactions. When you reduce a creature's HP to 0, you can generate an explosion on that spot. You innately cast Fireball as a free action on that spot without expending a spell slot, except the DC is equal to the creature's CR and the damage type of the Fireball is Radiant. The Fireball's spell level is equal to the level of your pact slot. A creature in the area of more than one burst is affected only once. You cannot not cast Fireball when you reduce a creature's HP to 0.

If another creature is reduced to 0 HP through this feature, you also innately cast Fireball at their location.

Since these Fireballs do not take an action to cast, they do not follow the ruling of Action-Bonus Action spellcasting and can be chained unlimited times.

Demolitionist

10th level feature

You know the best way to take structures down, and make your explosions more potent. You deal double the damage to all Constructs and non-living objects. Additionally, the radius of all your spells and effects that affect a spherical area is doubled.

Also, you have become battle-hardened from all your own explosions. If you are within the radius of your own spell or effect that affects a spherical area, you automatically succeed on the saving throw you are forced to make, and you take no damage on a success.

Heart of Fusion

14th level feature

Atoms do not merely split; they fuse as well, and you can be a Battery of Hope when the situation is dire. When you are reduced to 0 HP, you can generate an explosion centered on yourself, with a radius of 30 ft. (not affected by the 10th level feature's extended range). Allies within this area gain temporary hit points equal to the damage dealt by a Fireball at the highest level you can cast using a pact slot.