Inevitable Judgement + Hexblast

What kind of resistance will affect the chaos damage from a critical hit: the monster's resistance to chaos or the seemingly zero resistance to the elements?
It seems to me that this will be a monster's resistance to chaos.

It will do the same as it does without inevitable judgement because that just makes resist get thrown out, it doesn't set it to 0.

so damage will be resisted by a monsters lowest resist, if thats chaos it'll use that but if you've say applied a juiced flammability and a mob has -10% fire resist it will be resisted by fire then inevitable judgement will ignore it on a crit.

Pretty confident of this answer but as per usual for obscure interactions PVP is your best bet to test it out

For the sake of explaining I'll paint 2 scenarios, where you critically hit an enemy with Hexblast dealing 100 damage;

1. The enemy you hit has
20% fire res
20% cold res
20% lightning res
10% chaos res

In this scenario Hexblast looks at the resistance numbers and picks chaos resistance, because it is the lowest. Inevitable Judgement has no effect on chaos resistance and therefore you deal 90 chaos damage.

2. The enemy you hit has
-20% fire res
0% cold res
0% lightning res
-10% chaos res

In this case Hexblast picks fire res. Since Inevitable Judgement makes you ignore elemental resistances on crit you will deal 100 chaos damage.

Inevitable judgement does not reduce resistances to 0. It does not affect selecting which resistance is lowest, because these resistance numbers are not changed, they are just ignored for the purpose of dealing damage.