Formulas and Game Mechanics

Spellcasting

It should be noted that the casting focus referred to in the discussion below is not the skill, Focus.

Chance to Cast

The following information is gathered from UO Developer Wilki's statements on the Stratics message boards.

  • Chance to Cast = ( ( Skill - ( Difficulty - ( Casting Focus / 2 ) ) ) / Casting Focus )%
  • Chance to Cast can never be negative, nor over 100%.
  • The Minimum Skill Requirement to cast a spell exists two ways:

Definitions

  • Skill: The caster's skill level.
  • Casting Focus: A predetermined value that defines how wide the "window" is between 0-100%, centered on the difficulty value.
  • Difficulty: the point where you have 50% to succeed.
  • Minimum Requirement: Minimum skill level required before spell can be cast (even if the chance to cast is above 0).

Values


Casting Focus
Difficulty

Minimum skill need for 50% success chance to cast.

Bushido
Chivalry
Magery
Necromancy
Ninjitsu
Spellweaving
Mysticism


"Plain English" Version

  • Magery and Necromancy spells require 20 skill points above the minimum requirement to be cast 50% of the time, and 40 skill points above the minimum requirement to be cast 100% of the time.
  • Chivlary spells requires 25 skill points above the minimum requirement to be cast 50% of the time, and 50 skill points above the minimum requirement to be cast 100% of the time.
  • Bushido, Ninjitsu, and Spellweaving spells require 12.5 skill points above the minimum requirement to be cast 50% of the time, and 37.5 skill spoints above the minimum requirement to be cast 100% of the time.
  • All minimum requirements except for magery are listed in game. Magery minimum requirements can be found on UO.com: http://guide.uo.com/magic.html