Acolyte of Chayula Bugged or just Cooked?

-Event Horizon states a 3% loss of life and ES when casting chaos skill.
-Embrace the Darkness states Damage is taken from Darkness before Life and ES.

Why does it still cost life and ES when casting chaos skill? Is this a bug or intended. If intended, seems like another reason against ever taking this Ascendancy node.

TBH, the whole ascendancy seems like it was half baked... Mana leech only seems to work with physical damage. How many physical damage builds are going to stack ES and Mana? Why is there not a way to leech mana with spells? I missing something?