There is no possible way to determine how much temporary health pool a player has.
The only thing that can be done now, is the max health of type (type) - health of type(type) which only works if you are at full regular shields/health/armor
Thank you for your time.
If they did add this then they’ll need to have separate Temporary shields (Lucio, Doomfist, Sigma) and Temporary Armor(Brig) values.
On the off-chance I’ve misunderstood what you meant by temporary health pool, are you referring to the additional shields and armor a player gets from things like Rally and Sound Barrier, right?
Yes.
But bIizard(will remove name Immeditly if needed) has access to thoses values…
I’m not disagreeing with you. More tools the better.
I’m just adding to the thread that having separate return values for shields and armor respectively would be good functions to have. You can simply add both values together if you needed the total value.
Oh. Okay. Sorry. 
. And can you explain more about how I can get the amount of extra healthpool?(maybe I read this wrong)
No worries. 
I never did say that…
You could artificially track it depending what is adding to the health pool and add it to a variable but man that doesn’t seem like it’s worth the time.
What do you need it from?
I need it for this:
The deflect armor uses the temp. health, which is hard to keep track of…
Why not use a local Variable as the “temp health” instead?
I have an idea but I’m not sure if it’ll work. To my knowledge I’m not sure if you can make health a different color. I may be wrong I’ve never tried it but I don’t remember coloration being an option. Let me know if I’m wrong. Anyways, I kind of have an idea on how to do it. If I understand correctly, is it like a thorns kind of thing. Let me know if I’m wrong. If it is you could have a rule that says “Player received damage”, damage attacker. Damage amount would be “Multiply (Event damage) and 0.5” Then make it non-regenerable. Is it regenerable or obtainable after lost? Because you can make it so that this only happens when your health is greater than x amount because you couldn’t have it without full Heath. I’m not entirely sure how you would do it if damaged below that health point but you still have the “deflection health.” You could keep track of it with a variable so it mimics the change in that health. That could work. This is just an idea I may be wrong on something. 
It sort of reminds me of Doomfist’s passive… so I’m guessing you gain the armor through your abilities… although it is up in the air if the armor gradually over time is removed or it’s removed instantly after a duration of time.
C’mon. We need this! don’t give up guys!