[Update Notes: 2.02]

Draining had disappeared because of a bug which was fixed in 2.01.

 

BUT 2.0 had also introduced the Ambushing enchant, which drains attack speed and the duration of beneficial effects. Many items with Draining were given Ambushing too in addition, but it was bugged (it stole a lot more speed than it was meant to.)

 

So that's probably a typo in the patch notes.

In other words Draining stays Draining, and Fellstroke's/Spelltongue's Ambushing will be changed to 15%?

[Update Notes: 2.02]

Draining was changed from 20% damage done restored as endurance to some attack speed stealing non-sense. It was apparently a bug and was fixed. What's this 15% attack speed draining now? I'm confused.