Priest · Shadow Magic · tier 2 · from level 15

Shadow Affinity

Rank 3/3

Reduces the threat generated by your Shadow spells by 30%.

Doesn't change the damage or healing of any Priest spell.

Averages, counting crits and misses, for a level 60 Priest with a typical weapon and no other gear or buffs, against a target your level. Worked out from the game's own data, the same way as the Foresight addon.