Heal Scourge is different from the other support builds. It has low boon output, aside from some Might and some Regeneration, and has relatively low direct healing. Therefore this build will almost always be played as a second healer.
What this build does offer is Barrier, like a lot of Barrier. You can use this to predict when your squad will take damage and completely mitigate it. You also have quick access to fast resurrecting and can pull multiple Downed people together.
Heal Scourge is easy to gear and easy to use, however you will need a good understanding of raid mechanics to know when your squad will need barrier and when not to use it.
You need to be using your skills that generate Life Force off cooldown:
This will allow you to more freely spam your shroud skills, specifically .