The spell reads like this;
Cast Time - Instant
Target - Self
Duration - 12 Seconds
Cost - 200 ultimate
Ignite the molten lave in your veins, limiting incoming damage to 3% of your Max Health and dealing 889 Flame Damage to nearby enemies each second for 12 seconds.
When activated, nearby allies gain a damage shield for 100% pf their Max Health for 12 seconds.
Now reading this ability the way you would expect it to work is that it limits each hit of damage against you to 3% for the next 12 seconds. So basic maths would dictate that without any kind of self heals it would take 34 spells to kill you. 100 / 3 = 33.33 repeating.
Now with a global cool down of 1 second and the light attack weaving by pass. This means that a single person can hit you twice per second.
So in a 1v1 a single person would need to hit you 15 times.
Effectively according to the maths and the spell description it would be impossible in a 1v1 scenario for a person to kill you with it Active.
Even in a 2v1 scenario you should last 7.5 seconds with no healing.
But this spell does not always work this way. I am constantly being killed from full health 1v1 inside of the 12 second window. Which plain shouldn't happen because damage is supposed to be capped.
I literally just had a fight that led me to posting this. It was a 2v1 me being the 1. I had it up just before the first attack landed. But was killed inside of 3 seconds.
As the tool tip does not change it would be safe to assume this ability is not affected by battle spirit. And even if it were bringing the mitigation up to 6% (even though the tooltip does not change). Inside of 3 seconds would still = to a broken ability.
Mathematically this shouldn't have happened. So common sense would say that you @ZOS
need to fix this bug.