Some Sage Discussion

[Rilifane]

I would like Holos better if it applied just a shield with the damage reduction. Would feel easier to use since i wouldn’t be wasting that healing for the damage reduction.

You can chose how you want to use it depending on the scenario.
In trash pulls it's fantastic for healing the tank a bit and giving mitigation for a whooping 20s. Things start dying by the time it wears off.
For boss aoes it's just a regular heal, they don't hit hard enough to use it as mitigation even with vuln stacks.

In raids you can either leave some HP loss before the next raid wide so the initial heal tops the party off while the mitigation is for the aoe itself or, if everyone is already topped off, use it as an heal afterwards and either enjoy the mitigation for subsequent aoes or for the tank.

If you're using Holos on a single hit raid wide just for the mitigation when they'd survive without it, you're wasting its potential. If people survive it without additional 10% (you have a 10% mitigation on a 30s cooldown aswell), 300 potency heal is the stronger part as you'd have to heal afterwards either way.
You'd need to take almost twice as much damage as you have HP within 20s for the mitigation to outclass the heal when used like this. It's fantastic for aoe sequences like WL 2, Terminal, Cycles etc. And for all other scenarios it simple needs a bit of situational awareness.
Holos is one of the skills that rewards planned HP loss when used outside the abovementioned mechanics.