While using Stygian coal we used to be able to cast multiple instance of Drain life in previous patch, resulting in very high amount of stygian beam per second. However, I just realise that Drain life does not stack anymore, which is a super hard nerf for the stygian lich, was this explain in the patch note?
Apparently not, thost are all the Drain Life/Stygian Coal references I was able to find (search is a thing) from 1.2.