From what i read, maybe im misunderstanding it but
Energize: This skill now also triggers from Assassinate. It now triggers from damage dealt (rather than ability use) such that each hit of Assassinate, Thrash, and Lacerate have an individual chance to yield the Energize buff. The chance to trigger has been reduced to 30% per hit.
It now triggers from DAMAGE DEALT, not Ability Use, so there for, for each Thrash (Double Strike), it has 2 chances to proc Energize (Particle Acceleration), and with Lacerate (Spinning Strike), depending on the amount of mobs, each hit has a chance to proc Energize (Particle Acceleration).... get it? Thats why they lowered it to 30% chance to proc, because they had too, its actually a buff if this is correct.
Edit for Wither now proc'ing Harnessed Darkness /thread