0042-spell-effects.md

ADR 042: Spell Effects Implementation

Status

Accepted

Context

We have implemented spell casting (slot consumption) and concentration, but spells do not yet apply their primary effects: Damage and Healing. We need a standardized way to define and apply these effects.

Decision

We will expand the ISpell interface and CastSpellAction to handle damage and healing.

1. ISpell Interface:

   • IReadOnlyList<DamageFormula> Damage { get; }: A list of damage formulas (Dice + Type).
   • string? HealingDice { get; }: Dice formula for healing (e.g., "1d8").
   • SaveEffect SaveEffect { get; }: Enum defining effect of a successful save (None, HalfDamage, Negate).

2. CastSpellAction:

   • Will be responsible for rolling the dice.
   • Will iterate over targets (from ActionContext).
   • Will trigger saving throws on targets if required.
   • Will calculate final damage based on save result.
   • Will call target.HitPoints.TakeDamage or target.HitPoints.Heal.

3. 5e.tools Data:

   • We will parse the damage array for damage types.
   • We will parse healing entries (often in meta or inferred from description/school, but 5e.tools usually has specific fields for scaling). Correction: 5e.tools often puts healing in entries or specific scaling objects. We might need to look for specific tags or just parse the damage field which sometimes contains healing in other schemas, but for 5e.tools it's often distinct. We will start with standard damage parsing and look for healing property if it exists in the JSON, or infer from entries if needed.

Consequences

• Positive: Spells will finally have mechanical impact on HP.
• Negative: Parsing 5e.tools healing data might be complex as it's less standardized than damage.
• Risks: Complex spells (e.g. "Ice Storm" doing bludgeoning + cold) need careful parsing.

Technical Notes

• DamageFormula struct/class: { string Dice, DamageType Type }.
• SaveEffect enum: None, Half, Negate.