vulnerable vs. crit immunity

I honestly don't know - but if I had to guess, I would bet that vulnerable takes precedence- only because it is more rare and newer. I know that seems like a lame reason, but there is precedence for that particular precedent.

Crit immunity wins per swgoh.gg mechanics.

Crit immunity: +999900% crit avoidance
Vulnerable: -500000% crit avoidance

I stand corrected. Thank you Bulldog.