attempt_arcane_synthesis
Create custom spells dynamically in RPG sessions by specifying effects, targeting, and components, with success determined by difficulty checks and modifiers.
Instructions
Attempt to create a spell on the fly through Arcane Synthesis.
DC Calculation: Base DC = 10 + (Spell Level × 2)
Modifiers: +2 if in combat (encounter_id provided) +3 if novel effect (no similar spell known) -1 per 100gp of material component (max -5) -2 if related spell known -2 if school specialization -3 if near ley line/magical nexus -2 if celestial event (blood moon, eclipse) +2 if desperation/urgency
Outcomes:
Mastery (nat 20 OR beat DC by 10+): Spell works AND permanently learned
Success (beat DC): Spell works this time only
Fizzle (within 5 of DC): Slot consumed, no effect, minor mishap
Backfire (fail by 5-10): Spell damages caster (level × d6)
Catastrophic (nat 1 OR fail by 10+): WILD SURGE!
Spell Level Damage Guidelines: Level 1: Single 3d6, AoE 2d6 (10ft) Level 2: Single 4d6, AoE 3d6 (15ft) Level 3: Single 8d6, AoE 6d6 (20ft) Level 4: Single 10d6, AoE 8d6 (30ft) Level 5+: Progressively more powerful
Example: { "caster_id": "wizard-1", "caster_type": "character", "narrative_intent": "I weave shadows together to blind the orc chieftain", "proposed_name": "Shadow Blind", "estimated_level": 2, "school": "illusion", "effect_specification": { "type": "status", "condition": "blinded", "condition_duration": "1 minute" }, "targeting": { "type": "single", "range": 60 }, "saving_throw": { "ability": "wisdom", "effect_on_save": "negates" }, "components": { "verbal": true, "somatic": true }, "concentration": true, "duration": "1 minute" }
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| encounter_id | No | +2 DC if in combat | |
| caster_id | Yes | ||
| caster_type | Yes | ||
| narrative_intent | Yes | What spell effect the player wants | |
| proposed_name | No | ||
| estimated_level | Yes | ||
| school | Yes | ||
| effect_specification | Yes | ||
| targeting | Yes | ||
| saving_throw | No | ||
| components | Yes | ||
| concentration | Yes | ||
| duration | Yes | ||
| circumstance_modifiers | No | e.g., "near ley line", "blood moon" | |
| target_ids | No | ||
| target_types | No | ||
| sessionId | No |