User blog comment:Herzog de Puce/Baeny, the Mana Engineer/@comment-24364644-20140623134921/@comment-3148314-20140624083136

I noticed that the bonus damage on W didn't show.

0.5 / 1 / 1.5 / 2 / 2.5 % of max mana

so with 4000 mana this would give an additional +100 dmg at rank 5 while the ability is toggled.