Final Detonation

10th-level transmutation (forbidden)
Casting Time: 1 action
Range: Self (variable radius)
Components: V, S
Duration: Instantaneous
Prerequisites: 20th level, the ability to cast 9th-level arcane spells, attunement to an activated Weavebreaker

Core Concept:

The caster self-immolates in a detonation that tears the Weave, creating a magical singularity of destruction. The radius, damage, and zone effects all scale with the caster’s arcane energy reserves and remaining life force.

Blast Radius Calculation

Before casting, calculate the Total Spell Slot Energy Pool (TSSP):

Add the levels of all unused spell slots.
(e.g., 4×1st + 2×2nd + 1×5th = 4 + 4 + 5 = 13 points)

Blast Radius = TSSP × 500 feet

Example: 13 points × 500 ft = 6,500 ft (≈ 1.23 miles)

Proximity Zones (within radius)

Ground Zero (Inner Zone) – within 1/4 of total radius

• Damage: Caster’s current hit points × 4, force damage (no save)

• No resistance or immunity applies.

• All creatures, objects, terrain, and magical effects are disintegrated.

• Reality distorts—time and space are shredded. Only divine intervention or artifact-level shielding can protect.

Close Range (Middle Zone) – between 1/4 and 1/2 of total radius

• Damage: Caster’s current hit points × 2, fire + force damage
  
• DC 25 Dexterity save for half
  
• Creatures that fail are blinded and stunned for 1 minute.
  
• Nonmagical terrain is incinerated. Stone melts, wood becomes ash.

Outer Shockwave (Outer Zone) – between 1/2 and full radius

• Damage: Caster’s current hit points, fire damage
  
• DC 25 Constitution save for half
  
• Targets are knocked prone and pushed 60 feet away from Ground Zero
  
• Structures are shattered, windows explode for miles, and air pressure ruptures lungs of common creatures.

Caster’s Fate

• The caster dies instantly and is unresurrectable by any mortal means. Ao may decide to deny any attempts of resurrection.
  
• Their soul is scattered across the Weave, becoming a Plague Echo—a lingering arcane scar tied to the fabric of magic.
  
• A Weave Scar manifests at Ground Zero (see below).

Aftermath: Plagueblight Zone

A 1-mile radius from Ground Zero becomes a Plagueblight—an arcane dead/mad zone with traits reminiscent of the Spellplague.

Plagueblight Traits (Lasting decades or longer):

Spellcasting surge checks (d20):

• 1–5: Spell fails and causes a magical catastrophe (DM determines)
  
• 6–10: Spell backlashes; caster takes 3d10 force damage
  
• 11–20: Spell functions

• Creatures born or living here risk Plague Scars (mutations): glowing skin, split perceptions, reverse time-blinks, etc.
  
• Reality is unstable: doors open into voids, gravity shifts, ambient light pulses without source.

Weave Scar (100 ft radius epicenter)

This is the magical epicenter—a raw rift into the Weave.

• Spells behave chaotically (DM decides on a per-spell basis)
  
• Portals open at random
  
• Magic items can spontaneously awaken, break, or transmute
  
• The caster’s arcane echo may speak from here—or possess those who draw too deeply on magic