diehammer/Diehammer - 40k Die Modifier Research.md

Warhammer 40k Die Modifiers — Research (11th Edition, current as of Aug 2026)

Reference for the Diehammer app's die-modifier research task. Sourced from the 11th Edition core rules (released 2026) via Goonhammer/Tabletop Battles and ThriftHammer's keyword cheat sheet.

Core roll mechanics to support

• Flat modifiers to Hit: +1/-1. Net modifiers to a single hit roll are capped at ±1 regardless of how many sources stack.
• Flat modifiers to Wound: +1/-1. Same net cap of ±1 applies.
• Unmodifiable results: an unmodified roll of 1 always fails; an unmodified roll of 6 always succeeds (hit and wound rolls).
• Rerolls:
  • Reroll 1s (to hit or to wound)
  • Reroll all failed rolls
  • Reroll all rolls ("fishing" — used with Sustained Hits/Devastating Wounds to chase crits)

Hit roll keywords

• Sustained Hits X: unmodified hit rolls of 6 generate X additional automatic hits. Bonus hits are not themselves Critical Hits.
• Lethal Hits: unmodified hit rolls of 6 auto-wound (skip the wound roll). Not a Critical Wound, so the target still gets a save.
• Torrent: no hit roll at all — automatic hits equal to the weapon's Attacks characteristic.
• Psychic: ignores all modifiers to the hit roll (cover, stealth, etc. all disregarded).
• Heavy: +1 to hit if the firing model moved less than 3" that turn (unit-wide, all-or-nothing).
• Plunging Fire: +1 BS when shooting from 3"+ elevation.
• Indirect Fire: target always treated as in Cover (-1 to hit), no rerolls to hit allowed.
• Cover (changed in 11th): now a straight -1 to the hit roll, not a save bonus.
• Ignores Cover: negates the Cover -1 to-hit penalty.
• Stealth: grants the Benefit of Cover even in the open (was a direct -1 to hit in 10th).

Wound roll keywords

• Devastating Wounds: a Critical Wound (unmodified 6, or lower threshold via Anti) bypasses armor and invulnerable saves entirely. Only Feel No Pain can still apply.
• Anti-X (keyword) Y+: against units with the matching keyword, wound rolls of Y+ count as automatic Critical Wounds.
• Twin-linked: reroll wound rolls (ranged and melee).
• Lance: +1 to wound if the unit charged this turn.
• Critical Wound: bypasses all armor/invuln saves outright; only affects one model regardless of Damage stat.

Damage-stage modifiers (not hit/wound, but relevant to a full simulator)

• Melta X: +X Damage when firing within half range (roll separately for models in/out of half range; apply after base damage, before damage-reduction effects).
• Feel No Pain X+: post-save roll-off to ignore a wound entirely.
• Hazardous: post-attack self-damage roll (fail on 1-2 → Mortal Wound(s), no saves).

Implications for Diehammer's modifier system

To "accommodate" this fully, the die-modifier engine likely needs to support, per roll type (hit/wound/save):

1. A stacking flat-modifier input, auto-capped at ±1 net (hit/wound only — saves aren't capped the same way, since AP reduces save target directly rather than via a capped modifier).
2. A reroll mode selector: none / reroll 1s / reroll all failed / reroll all.
3. A "critical trigger" layer separate from raw success — since Sustained Hits, Lethal Hits, and Devastating Wounds all key off unmodified natural 6s (or a lowered Anti-X threshold), not the modified result.
4. Flags for "ignore all modifiers" (Psychic) and "auto-success, no roll" (Torrent).