Priest · Discipline · tier 4 · from level 25

Improved Mana Burn

Rank 2/2

Reduces the casting time of your Mana Burn spell by 1.0 sec.

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.