gogobee/REBALANCE_NOTES.md

Combat Rebalance — 2026-05-10

Post HP-unification balance recovery. Player HP dropped ~45% when the legacy 50 + CombatLevel*2 base was retired; monsters were still tuned for the old ~120 HP scale, making even L1 dungeons unsurvivable. This pass retunes both sides for the dnd HP scale and retires CombatLevel from combat formulas.

Symptom

Real prod player @holymachina (cleric, dnd L10): legacy combat MaxHP ≈ 165 → post-unification combat MaxHP ≈ 70. Monster damage formulas still scaled quadratically with tier (T5 Attack=49), oversized for ~70 HP players. Wight encounter user reported: 56/56 → 0/56 in 4 phases despite wight ending with 12 HP left. Even fresh L1 dungeon dives ran 95%+ death rate in sims.

Root causes

1. HP unification dropped the 50 + CombatLevel*2 base without any rebalance pass on monster formulas. Monsters tuned for legacy HP pool now obliterate dnd HP pool.
2. Tiebreak was absolute-HP-based (recent change de02907). Worked OK on legacy scale where pools were similar; breaks on dnd scale because monster pools (~30–175) are 2-3× larger than player pools (~13–83), so timeouts always favor monsters even when player took less proportional damage.
3. CombatLevel was still load-bearing in DerivePlayerStats for Attack/Defense/Speed/HP scaling, contradicting the Phase L closeout that retired it everywhere else. This made test fixtures lie about real player power.

Scope decisions (locked in by user)

• Don't restore the legacy 50 + CL*2 HP base. Combat MaxHP stays at c.HPMax + HPBonus(gear delta only).
• Strip CombatLevel from combat scaling entirely. Player power = ability scores + gear + dnd-derived layers (AC/AB/weapon dice). No level-based defense/speed/attack/HP scaling on the player side.
• Both formula and (eventually) bestiary tuning for monsters, not just one. Formula pass was sufficient this round; bestiary deferred.

Changes

Test infrastructure

internal/plugin/combat_stats_test.go:

• TestBalanceRegression_DungeonDeathRates and TestBalanceRegression_UnderleveledPlayers now apply the production combat pipeline before simulating: applyDnDPlayerLayer, applyDnDEquipmentLayer, applyDnDDungeonMonsterLayer. Previously they ran raw DerivePlayerStats output, which silently hid the HP-unification regression because the legacy MaxHP value never made it into the test combatant.
• New helper balanceTestDnDChar(dndLevel int) synthesizes a fighter sheet (mirroring autoBuildCharacter) at the requested dnd level. Replaces the old level=CombatLevel proxy.
• Test cases re-keyed onto dnd levels (1, 2, 5, 7, 9) for the well-geared baseline and (1, 2, 4, 6) for the underleveled set. Previously level=5..48 was being treated as both CombatLevel and dnd_level which hid the regression.
• Test log line now prints AC / AB / Atk instead of legacy Atk/Def/Spd triple — the d20 path's actual hit/damage drivers.
• TestDerivePlayerStats_BaseStats updated: zero-gear baseline is now MaxHP=50, HPBonus=0, Attack=5 (constants, no level scaling). Previously expected >=70 HP which was the legacy formula output for L10.

Player stat derivation

internal/plugin/combat_stats.go:

• Stripped CombatLevel scaling from DerivePlayerStats. MaxHP baseline is a flat constant (50, used only as the multiplicand for armor/arena/housing % bonus formulas — subtracted out into HPBonus at the end so the legacy base never reaches combat). Attack, Defense, Speed are now constants (5, 3, 5) plus gear and bonuses. Player power scales through gear and the dnd layers.
• All other gear/arena/housing/streak/grudge/pet/NPC bonus paths preserved.

Dungeon monster formulas

internal/plugin/combat_stats.go: DeriveDungeonMonsterStats:

Stat	Old formula (legacy HP era)	New formula (dnd HP era)
MaxHP	25 + t*t*6 + death*0.6 (T1=33, T5=187)	12 + t*7 + death*0.3 (T1≈22, T5≈65)
Attack	3 + death*0.2 + t*t*1.5 (T1=5, T5=49)	t*1.5 + death*0.04 (T1=1, T5=9)
Defense	2 + t*1.5	2 + t*1.2 (small trim)

Speed / CritRate / DodgeRate / BlockRate unchanged. AB scaling via applyDnDDungeonMonsterLayer (9 + tier) untouched — it was already calibrated for the d20 hit-resolution side.

Quadratic t*t*X terms are out everywhere on the monster side. Linear scaling matches the dnd HP scale's narrower band (player HP 13–83, not 60–200).

Tiebreak

internal/plugin/combat_engine.go:

• Reverted the recent absolute-HP tiebreak (de02907) back to HP percentage for the post-Sudden-Death timeout case. Bias toward player on exact ties (playerFrac >= enemyFrac → enemy dies).
• Reasoning: monster pools on the dnd scale are systematically 2-3× larger than player pools, so absolute always favored monsters even when the player took less proportional damage. The de02907 example case (88/123 vs 83/97) doesn't exist on the new scale.

Comments and tests touched (no behavior change)

• combat_stats.go comments rewritten to explain the dnd HP scale assumption and why the legacy base is captured then subtracted out.
• combat_engine.go tiebreak comment rewritten with the new rationale.

Sim results

go test ./internal/plugin/ -run TestBalanceRegression -v after this pass:

Well-geared at tier (target window in parens):

Dungeon	Player	Monster	Death rate	Target
Soggy Cellar (L1 T1)	HP=13 AC=12 AB=6	HP=21 AC=10 AB=5 Atk=1	3%	0–5% ✓
Goblin Warrens (L2 T2)	HP=23 AC=12 AB=6	HP=31 AC=11 AB=6 Atk=3	7%	0–10% ✓
Cursed Crypt (L5 T3)	HP=48 AC=14 AB=7	HP=42 AC=12 AB=7 Atk=5	1%	0–15% ✓
Troll Bridge (L7 T4)	HP=66 AC=15 AB=7	HP=53 AC=13 AB=8 Atk=7	8%	0–25% ✓
Abyssal Maw (L9 T5)	HP=83 AC=16 AB=8	HP=65 AC=14 AB=9 Atk=9	7%	1–35% ✓

Underleveled / undergeared (real danger expected):

Scenario	Player	Monster	Death rate	Min target
L1 in T2	HP=12 AC=12 AB=6	HP=31 Atk=3	84%	≥40% ✓
L2 in T3	HP=21 AC=12 AB=6	HP=42 Atk=5	99%	≥30% ✓
L4 in T4, T2 gear	HP=39 AC=12 AB=6	HP=53 Atk=7	97%	≥25% ✓
L6 in T5, T3 gear	HP=56 AC=14 AB=7	HP=65 Atk=9	83%	≥30% ✓

All pass. No other plugin tests broken by the rebalance (two pre-existing failures — TestStandaloneHarvest_RoutesToZoneRun and TestZoneRunFlow_AdvanceToBossAndComplete — are Phase G branching-zone node-naming issues, not caused by these changes; verified by stash-pop comparison).

Bestiary stat-block pass

internal/plugin/dnd_bestiary.go:

• Programmatic CR-based rescale of Attack and AttackBonus across all 69 entries. New formula:
  • Attack = round(1 + 1.5 × CR), with a gentler bend at CR ≥ 10 (max(prev, round(1 + 1.7×CR − 2))), capped at 38.
  • AttackBonus = min(old_AB, 11) — caps the d20 to-hit bonus so end-game monsters still miss player AC sometimes.
• HP / AC / Speed / Ability / BlockRate untouched — these aren't the lethality drivers; HP only matters if players can't damage-race the pool, and post-Attack-nerf the race is winnable.

Sample reseats:

Monster	CR	Old Atk → New	Old AB → New
Goblin	0.25	6 → 1	4
Skeleton	0.25	8 → 1	4
Wight	3	14 → 6	4
Flameskull	4	18 → 7	5
Troll	5	22 → 8	7
Wyvern	6	28 → 10	7
Thornmother (CR 11 boss)	11	32 → 18	8
Belaxath (CR 19 boss)	19	58 → 31	11 (was 12)
Ancient Dragon (CR 20)	20	65 → 33	11 (was 14)
Infernax (CR 24, end boss)	24	65 → 38	11 (was 14)

Test update: TestBestiaryToCombatStats dragon AB expectation 14 → 11.

Reasoning for not also touching HP: a CR 24 boss with 546 HP is appropriately big-boss bulky on the dnd scale — players doing 7-15 dmg/round will need 35+ rounds to kill, which is fine for a final boss with phases. The pain point was the boss one-shotting players via 65-damage swings, not the HP wall. If specific bosses still feel too tanky once players actually fight them, individual HP trims are easy.

Open follow-ups

• Arena monster formula (DeriveArenaMonsterStats) still has the old quadratic-feeling shape but isn't currently broken in sims — left untouched this pass. If arena death rates report wrong, mirror the dungeon shape.
• TwoHandedMode / Versatile weapon damage paths in applyDnDEquipmentLayer weren't audited this pass — if they're miscalculating damage dice, balance shifts.
• Tiebreak bias is a flat "player wins ties." Could be tuned to a small grace margin (e.g., player wins if playerFrac >= enemyFrac - 0.05) if narrative feedback says timeout losses still feel cheap.

Phase G test catch-up (formerly flaky)

Four tests written against the pre-Phase-G linear-room model were intermittently failing. Fixed in the same session so the suite runs clean:

• TestStandaloneHarvest_RoutesToZoneRun — was asserting the legacy <zone>.r1 node id; production now writes <zone>.entry from the registered graph. Switched to harvestNodeIDFor(run) so the test reads whatever production wrote.
• TestZoneRunFlow_AdvanceToBossAndComplete — asserted len(RoomsCleared) == TotalRooms. Diamond/fork graphs yield shorter paths than the total node count. Loosened to 1..TotalRooms (boss-defeated check still in place).
• TestZoneCmd_AdvanceFinalRoomBumpsMood — looped exactly TotalRooms markRoomCleared calls; with branching the run completes early and the extra calls find no active run. Switched to break on the first empty next return.
• TestAdv2Scenario_ZoneRunGoblinWarrens — sent only !zone advance, stalling at fork rooms (Phase G goblin warrens is a diamond graph). Added auto !zone go 1 when run.NodeChoices is non-empty so the scenario commits the first fork option and continues.

Verified clean across 4 consecutive go test runs.

Files touched

• internal/plugin/combat_stats.go — DerivePlayerStats CL strip, monster formula retune
• internal/plugin/combat_engine.go — tiebreak revert
• internal/plugin/combat_stats_test.go — production-accurate test pipeline, dnd_level-keyed cases, base-stats expectations
• internal/plugin/dnd_bestiary.go — programmatic CR-based Attack/AB rescale across 69 entries
• internal/plugin/dnd_bestiary_test.go — dragon AB expectation updated