Sustain is trash on PTS without blood for blood on magDK and I'm sure many other classes.
Blood for blood was gutted because it was either too powerful in the eyes of the developers or because they wanted people to use other spammables.
My suggestion is, for one, to make it not a useless skill, but two, also make other spammables viable.
Blood for Blood, make it still cost magicka and a reverse execute multipler: the more health you have the more it hurts, probably like 10%.
Controlled Frenzy ( morph of frenzy I imagine remove the one that heals )
No longer grants damage or makes you unable to heal, instead make spammables all cost health while toggled.
This means stam could be a vampire if they wanted,
This means I can use whip instead of blood for blood but still be a vampire.
This means you can literally not butcher one of the only things vampire has going for it.
This would open many possibilities for builds.
Jodynn PC NA
PvE and PvP MagDK
The lack of communication from ZOS to player speaks volumes.