Spell hit in classic WoW is the chance a spell lands on a higher-level target; it is a 4% base miss at equal level rising to 17% three levels up.
base chance to miss: same level 4%, +1 level 5%, +2 levels 6%, +3 levels 17%
+spell hit% from gear and talents is taken off, but the chance to hit never passes 99%
Spells are not affected by weapon skill or defence, only by the level difference, and the jump at three levels is large: a level-63 boss resists one spell in six until the caster finds 16% spell hit, after which nothing more helps.
| Caster at 60 | Base miss | Hit needed for 99% |
|---|---|---|
| Level-60 target | 4% | 3% |
| Level-62 target | 6% | 5% |
| Level-63 target (raid boss) | 17% | 16% |
Last checked: unverified against Forever. These are the long-established values of the classic ruleset (the 1.x game of 2005-2006); World of Warcraft Forever is in beta and may differ. When you test this one in Forever, post your numbers in Theorycraft.