Casting success and skill thresholds
From UO:PvE Wiki
A spell’s listed minimum is the beginning of its skill-check range, not a guaranteed successful cast.
Development source reviewed on 29 October 2026. In-game availability is unverified.
Chance formula#
For an ordinary skill-based spell check with minimum L and maximum U: chance = clamp((effective casting skill−L)÷(U−L),0,1). The casting-skill roll is separate from resistance, target validity and resource checks.
Magery by circle#
| Circle | Book minimum | Book 50% | Book 100% | Scroll minimum | Scroll 100% |
|---|---|---|---|---|---|
| 1 | −18 | 2 | 22 | −46 | −6 |
| 2 | −4 | 16 | 36 | −32 | 8 |
| 3 | 10 | 30 | 50 | −18 | 22 |
| 4 | 24 | 44 | 64 | −4 | 36 |
| 5 | 38 | 58 | 78 | 10 | 50 |
| 6 | 52 | 72 | 92 | 24 | 64 |
| 7 | 66 | 86 | 106 | 38 | 78 |
| 8 | 80 | 100 | 120 | 52 | 92 |
Other schools#
Necromancy normally uses [required skill, required skill +40]. A Necromancy scroll sets both endpoints to the required skill: below that requirement it fails, and at or above it the skill check succeeds. Chivalry normally uses [required skill, required skill +50].
Negative table thresholds mean a nonnegative skill already exceeds that point. A spell can still be blocked by missing resources, invalid targets, paralysis or other explicit conditions even when its skill check is guaranteed.
Source notes
Show 6 references
These references identify the reviewed shard files. Source presence does not establish live availability.
Projects/UOContent/Skills/SkillCheck.cs:48
Skill range and linear success chanceProjects/UOContent/Spells/Base/MagerySpell.cs:15
Current Magery difficulty tableProjects/UOContent/Spells/Base/MagerySpell.cs:44
Book and scroll indexingProjects/UOContent/Spells/Base/Spell.cs:619
Casting skill checkProjects/UOContent/Spells/Necromancy/NecromancerSpell.cs:37
Necromancy range and scroll exceptionProjects/UOContent/Spells/Chivalry/PaladinSpell.cs:126
Chivalry success range
Category: Character & combat