I really want to steal the essence, but maybe it would be more useful to steal mana? In case of a second failure, at least there will be a reserve for the abyss, and we need to help the guys deal some damage.
If you steal mana, either from C2 (if still alive) or C4 (if C2 is dead). I'll step away for a while, so you can confirm without me, once you've decided on the final option.