Warlock · Affliction · tier 4 · from level 25 · needs Amplify Curse

Curse of Exhaustion

Rank 1/1

Reduces the target's movement speed by 30% for 12 sec. Only one Curse per Warlock can be active on any one target.

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

Averages, counting crits and misses, for a level 60 Warlock 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.