Hit chance¶

Hit chance is the probability that a swing connects (vs. being dodged). It's evaluated before damage rolls.

The formula¶

Lyonspyre uses the pre-AOS T2A formula, with PvM-only specialty and talent bonuses layered on:

T2A hit chance

chance = (atkSkill + 50) / ((defSkill + 50) × 2)
       + SpecialtyHitBonus%/100
       + ArcheryVsHinderedBonus%/100      (archery only)
       ─ FencingCrippleDefenseScalar      (PvM melee only, scales defSkill)

The final value is then passed to a skill check — meaning:

A hit at chance >= 1.0 is auto-success and still triggers a skill-gain check.
A miss decrements no resource — you just don't connect.
atkSkill is the weapon's primary skill (Swordsmanship / Macing / Fencing / Archery / Wrestling for fists).
defSkill is whatever skill the defender's currently-equipped weapon uses (typically the same skill they'd swing with). Unarmed defenders use Wrestling.

Base chance table (pre-bonus)¶

100 weapon-skill attacker vs. defender of the listed weapon-skill, with no talents/specialties:

Defender skill	Base chance
30	93.75% (150 / 160)
60	68.18% (150 / 220)
90	53.57% (150 / 280)
100	50.00% (150 / 300)
120	44.12% (150 / 340)

The formula is symmetric: at equal skill the chance is exactly 50%. Each +30 attacker skill above defender adds roughly +10% in this range; each +30 defender skill above attacker subtracts roughly the same.

General-purpose attackers¶

For an attacker at lower skill levels:

Attacker	vs def-30	vs def-60	vs def-90	vs def-100
50	62.50%	45.45%	35.71%	33.33%
75	78.12%	56.82%	44.64%	41.67%
100	93.75%	68.18%	53.57%	50.00%
120	100.0%*	77.27%	60.71%	56.67%

* Chance is clamped only >= 0.02 in the AOS branch; in T2A there is no upper clamp, so high-skill-vs-low-skill chances above 1.0 still pass CheckSkill automatically and gain skill at the cap.

Bonus sources¶

Lyonspyre layers these on top of the base T2A formula:

Source	When
Specialty hit-chance	Returns percentage points (e.g. `5` = +5%). Always queried.
Archery vs. Hindered	Per-rank percentage points; only fires when the defender is hinder-tagged (PvM only).
Fencing Cripple	PvM-only; multiplies defender skill by a 0–1 scalar. 8% per stack (max 24% defense reduction).
Tier accuracy on the talent ladder	See Dungeon Talents.

Post-T2A hit-chance sources that do NOT apply

Later UO eras sum many additional sources into hit chance: AttackChance item property, Divine Fury, Animal Form (wolf / kitsune +20%), Hit Lower Attack / Defense, weapon-ability accuracy bonuses, special moves, Force Arrow, Block, Surprise Attack, and defender-side Discordance. None of these fire on Lyonspyre.

Discordance does fire in the T2A swing-speed formula but not in the T2A hit-chance formula — that's the original T2A behaviour, not something we've stripped.

Auto-hit / auto-miss¶

Pure T2A has no upper clamp: a 120-skill attacker vs. a 30-skill defender passes CheckSkill ~100% of the time.
Pure T2A has no 2% lower clamp either (the chance < 0.02 floor is AOS-only). If ourValue is tiny or theirValue is huge, chance can fall to zero.
CheckSkill itself still rolls — so even at calculated 95% you can miss the 1 in 20.