Cataclysmist Prestige Class

Prestige Class: Cataclysmist

Requirements To qualify for the Cataclysmist prestige class, a character must meet the following prerequisites:
Ability to cast at least one 3rd-level or higher spell that deals damage
Must be a Sorcerer, Wizard, Cleric, or Warlock
Level Progression & Features
5th Level – Mastery of Destruction
Upon entering this prestige class, you gain the ability to create Aetheric Charges whenever you cast a leveled spell that deals damage of your chosen elemental mastery. Each qualifying spell cast grants one charge, up to a maximum of six. When you reach six Aetheric Charges, you may expend them all to cast Paradox without using a spell slot. Paradox deals massive damage based on your chosen mastery’s element. When cast, Paradox forces all creatures of your choice within a 30‑foot radius sphere centered on a point you can see to make a saving throw appropriate to the element (Dexterity for Fire, Lightning, or Thunder; Constitution for Cold or Shadow; Intelligence for Psychic; Wisdom for Arcane). On a failed save, they take 4d10 damage of your chosen element, or half as much on a success.
This damage increases to 6d10 at 10th level, 8d10 at 13th level, 10d10 at 15th level, and 12d10 at 18th level. Additional effects may be described by the DM to reflect the element’s destructive nature (such as setting terrain aflame for Fire, suppressing magic in an area for Arcane, or chilling ground for Ice).
At 10th level, Mastery of Destruction improves:
You may now choose to gain either Shadow Mastery or Arcane Mastery.
Instead of immediately expending six Aetheric Charges to cast Paradox, you may choose to condense them into an Aetheric Token. This Token can be held and later expended to cast Despair, a devastating single‑target shadow spell. When you unleash Despair, the target must succeed on a Charisma saving throw or take 6d12 necrotic damage and be frightened of you until the end of your next turn (half damage and no fear on a success). The damage of Despair increases to 8d12 at 15th level and 10d12 at 18th level.
At 15th level, Mastery of Destruction improves further:
You may now choose to gain either Dreadfire Mastery or Radiantflame Mastery.
Whenever you cast a spell that deals damage of the element tied to your chosen mastery (Dreadfire or Radiantflame), you also gain a Flare Token. When you accumulate six Flare Tokens, you may expend them to cast Flare Star without using a spell slot. Flare Star creates a 40‑foot radius explosion of your chosen element centered on a point within 120 feet. All creatures in the area must make a saving throw (Constitution for Dreadfire, Dexterity for Radiantflame). On a failed save, they take 10d10 damage of the corresponding element, or half as much on a success. The damage of Flare Star increases to 12d10 at 18th level.
3rd Level – Elemental Focus
Choose one element to specialize in: fire, ice, lightning, thunder, psychic, shadow, arcane. This choice grants you additional features and shapes your later abilities.
Fire Mastery: Your fire spells deal additional damage equal to your spellcasting modifier + half your proficiency bonus (rounded up).
Ice Mastery: When you deal cold damage, targets hit must succeed on a Constitution saving throw or suffer Creeping Frost. A creature under Creeping Frost grants advantage to all opportunity attacks made against it until the start of your next turn.
Lightning Mastery: Your lightning spells now arc with volatile energy. When you deal lightning damage with a single-target spell, the spell arcs to one enemy of your choice within 5 feet of the original target, dealing half the original damage. In addition, your lightning spells ignore resistance to lightning damage.
Thunder Mastery: When you deal thunder damage, creatures hit must succeed on a Constitution saving throw or be deafened until the end of your next turn. Additionally, unattended objects within 10 feet of the target may be damaged or destroyed at the DM's discretion.
Psychic Mastery: When you deal psychic damage, targets must succeed on an Intelligence saving throw or have disadvantage on their next attack roll or saving throw before the end of your next turn.
Shadow Mastery (Available at 10th level only): When you deal shadow damage, targets struck also lose maximum hit points equal to the shadow damage dealt until they finish a long rest. This prevents that amount of healing until the effect ends.
Arcane Mastery (Available at 10th level only): When you deal arcane damage with a spell that natively inflicts arcane damage, targets must succeed on a Wisdom saving throw or gain Weakness to Magic until the end of your next turn. While under this effect, they suffer disadvantage on saving throws against magical effects, and spell attack rolls made against them have advantage.
Dreadfire Mastery (Available at 15th level only): Your dreadfire spells ignite lingering corruption. Targets hit take necrotic damage equal to your proficiency bonus at the start of their next turn. Additionally, dreadfire ignores resistance to fire or necrotic damage.
Radiantflame Mastery (Available at 15th level only): Your radiantflame spells blaze with purifying fire. Creatures damaged must succeed on a Constitution saving throw or be blinded until the end of their next turn. Radiantflame damage also bypasses resistance to radiant or fire damage.
7th Level – Elemental Mastery
Whenever you cast a spell that deals damage matching your chosen mastery, you add an additional damage die. In addition, creatures with immunity to that damage type are instead treated as resistant, and creatures with resistance are treated as taking full damage.
10th Level – Elemental Surge
At this level your control over destructive energy deepens. When you cast a spell of your chosen mastery, you may expend any number of stored Aetheric Charges to empower it. For each charge expended, the spell deals one additional die of damage of the same type. You may declare this after casting the spell but before damage is rolled.
15th Level – Elemental Fusion
At this level, your mastery reaches a breaking point where elemental forces intertwine. Once per long rest, when you cast a damaging spell of your chosen mastery, you may fuse it with a secondary mastery you know (such as one gained at 10th or 15th level). The spell deals its normal damage, plus half as much damage of the secondary mastery’s type. In addition, the spell applies the rider effect of the secondary mastery.
Sample Fusion Effects:
Fire + Ice: The target is both burned and slowed, taking fire damage and suffering Creeping Frost.
Lightning + Psychic: The spell arcs to an additional enemy and imposes disadvantage on the target’s next saving throw.
Thunder + Shadow: The target is deafened and loses maximum hit points equal to the shadow damage dealt.
Arcane + Radiantflame: The target gains Weakness to Magic and must save or be blinded until the end of their next turn.
Dreadfire + Fire: The flames ignite corruption that continues as necrotic damage and bypasses resistance.
The DM may create additional combinations based on campaign needs, ensuring each fusion feels distinct and thematically powerful.
Mastery Class: Master of Cataclysm
15th Level – Empowered ChannelingUpon ascending to the Mastery Class, you gain the ability to channel the destructive essence of your Aetheric and Flare resources into a single overwhelming strike. When you cast a spell of your chosen mastery, you may expend all stored Aetheric Charges, Aetheric Tokens, or Flare Tokens to empower it. For each charge or token expended, roll one additional damage die of the same type. If you expend a Token (Aetheric or Flare), the spell also automatically applies the rider effects of your secondary mastery, as if using Elemental Fusion.
You may use this feature once per long rest. After regaining its use, any unused charges or tokens vanish, their energy consumed by your soul’s burning need for destruction.
17th Level – For the Love of ExplosionsYour destructive instincts reach apocalyptic levels. When you expend Flare Tokens to cast Flare Star, you may also trigger Paradox or Despair in the same action. These spells resolve immediately after Flare Star, representing a catastrophic overload of elemental magic. This feature may be used once per long rest.
20th Level – Meteoric AscendanceYour mastery culminates in the ultimate spells of devastation. Whenever you cast Paradox, Despair, or Flare Star, you also gain one Meteor Token. When you accumulate four Meteor Tokens, you may expend them all to cast Meteor without using a spell slot. Meteor calls down a single blazing celestial body upon a point you can see within 1 mile. The impact devastates a 100-foot radius area. All creatures in the area must make a Dexterity saving throw, taking 20d12 bludgeoning and 20d12 fire damage on a failed save, or half as much on a success. Massive structures, fortifications, and terrain features in the area are flattened or annihilated at the DM’s discretion.
Alternatively, you may condense four Meteor Tokens into a single Ultima Token. If you accumulate two Ultima Tokens, you may expend them to cast First Ultima without using a spell slot. First Ultima unleashes a cataclysm beyond mortal comprehension. A massive sphere of annihilation expands in a 120-foot radius centered on you or a point you can see within 500 feet. All creatures in the area must make a Constitution saving throw, taking 25d12 force damage and 25d12 radiant damage on a failed save, or half as much on a success. Structures, terrain, and magical effects in the area are obliterated at the DM’s discretion. After using First Ultima, you immediately drop to 0 hit points and automatically begin rolling death saving throws at the start of your next turn, overwhelmed by the strain of channeling the absolute pinnacle of destructive magic.