Once Triggered Immunity has proc'd, taking a hit that would otherwise deliver damage of the type you're already immune to; which would also proc Triggered Immunity, heals both endurance and health to full.

 

I'm not certain of my explanation, but it seems to fit what I've experienced.

 

A separate potential issue with Triggered Immunity is that once it procs for one damage type, if proc'd again for a different damage type, while still immune to the first damage type, the first immunity is cancelled. I don't know if that's an intended mechanic, it just seemed counter intuitive given you get two uses of the ability per encounter.

 

Thanks!

To follow up, I had some more time to investigate the first issue I mentioned:

 

http://imgur.com/a/n9GHq

 

In the above scenario the first unstable construct (not pictured) had exploded activating 21 sec. of burn damage immunity. The second construct also then activated self destruct, but rather than simply being immune to that damage type, my fighter healed to full. Even misses seemed to produce the same heal effect.

Hey snowballing,

 

Thanks for bringing this to our attention. I put in a bug about the triggered immunity healing. As for the issue with the immunity type changing and the first one canceling, this is intended.

 

Thanks!