Where does the healing source comes from ?

Hey guys I’ve been trying out this build I’m currently in the start of act 3 cruel so there’s quite a few passives missing a but nothing that important tbh I should be able to do it

there’s something I’m missing I think, the infernal flame just kills me every time and when I have seen gameplay of this their infernal flame doesn’t exceed 50% and yet they spam the comet like crazy, there’s this passive that makes your potion heal energy shield and makes your health recharge instead ( this doesn’t happen while in demonform ), I’m wondering how this passive helps because to me it makes my build unplayable now my demon form will deplete my health and I will have no way to regain that health, since my flasks will only heal energy shield does anybody knows what could be going on ?

I’ll leave the max roll guide link here in case you want to check it, and as reference I got pretty much comparable gear and only missing a few passives from the build since I’m level 60

https://maxroll.gg/poe2/planner/kdd790fa