Резисты

[Serafimka]

http://wowwiki.wikia.com/wiki/Resistance
For binary spells
Resistance reduced the chance for the binary spell to land by a certain percentage. Spell hit would not reduce this chance. It was assumed that this percentage was exactly the damage reduction percentage given above.
Binary spells were spells which dealt a debuff (like [Frost Nova] or [Vampiric Embrace]) or, for some other reason, needed to take full effect or no effect at all.

а выше там написана формула снижения дамага для обычных спелов