my favorite part is the abyssal drain charges, but combine oblation into AD. AD would just add the effect of oblation. I don't love the idea of a per hit heal, bc then you just have bloodwhetting, which I think is the equivalent of an in game cheat code.
I'd pick one or the other between AD chargesand a TBN HoT. for the same reason, it would make trash pulls too easy.

A bigger issue to me is that * of darkness/shadow is repetitive after a while. GNB has fated circle after ever 1-2 aoe, now with a continuation. Then it has burst strike after every aeo, but you rarely even need to use it because you're saving cartridges for gnashing fang.. GNB has so many options that you don't even have to use them all.
reducing the blood gauge cost on quietus and bloodspiller to 25 would really go a long way imo just simply to make it more interesting, or give us a better 50 cost option and a 25 cost option.