3.0 KiB
Research: Display Initiative
R-001: Initiative Calculation Formula (2024 Monster Manual)
Decision: Initiative modifier = DEX modifier + (proficiency multiplier × proficiency bonus)
Rationale: The 2024 Monster Manual changed how monster initiative works. Instead of always using the raw DEX modifier, creatures can add their proficiency bonus (or double it) to initiative. The 5etools JSON encodes this as "initiative": { "proficiency": N } where N is 0 (absent), 1 (proficiency), or 2 (expertise).
Verification: Aboleth (DEX 9, CR 10, initiative.proficiency = 2) → DEX mod (−1) + 2 × PB (4) = +7. Matches D&D Beyond display of "Initiative +7 (17)".
Alternatives considered:
- Store pre-calculated initiative in bestiary data: Rejected — violates deterministic domain core principle; calculation is simple enough to derive.
- Use a lookup table from 5etools: Rejected — 5etools doesn't provide a pre-calculated value, only the proficiency multiplier.
R-002: Passive Initiative Value
Decision: Passive initiative = 10 + initiative modifier
Rationale: Follows the standard D&D 5e passive check formula (10 + modifier), same as passive Perception. Used for fixed initiative when DMs skip rolling.
Alternatives considered: None — this is the standard formula with no ambiguity.
R-003: Display Format
Decision: "Initiative +X (Y)" with explicit sign for positive values and minus sign (−, U+2212) for negative values.
Rationale: Matches the Monster Manual 2024 stat block format exactly. The parenthesized value is the passive initiative. Zero modifier displays as "+0".
Alternatives considered:
- Omit passive value: Rejected — the MM 2024 format includes it and it's useful for quick reference.
- Use hyphen-minus for negatives: Rejected — official materials use the typographic minus sign (−).
R-004: Placement in Stat Block
Decision: Display initiative on the same line as AC in the stat block header, matching MM 2024 layout ("AC 17 Initiative +7 (17)").
Rationale: The 2024 Monster Manual places AC and Initiative on the same line in the stat block header. This is the most natural position for DMs familiar with the new format.
Alternatives considered:
- Separate line below AC: Matches older stat block formats but deviates from MM 2024.
- Above ability scores: Too far from other combat stats.
R-005: Raw JSON Structure for Initiative
Decision: Parse initiative.proficiency from the raw 5etools monster object. Treat absent initiative field as proficiency multiplier of 0.
Rationale: The 5etools JSON format uses "initiative": { "proficiency": 2 } for creatures with initiative expertise. Not all creatures have this field — absence means no proficiency is added (raw DEX modifier only).
Data sample (Aboleth):
{
"name": "Aboleth",
"initiative": { "proficiency": 2 },
"dex": 9,
"cr": "10"
}
Alternatives considered: None — this is the canonical 5etools format.