AoS Jaws like a steel trap vs invulnerable saves.

[Jason839]

Does the Kroxigor Like a Steel Trap rule prevent models from making mortal wound saves after the mortal wounds are assigned? It says they do not make a save but that is before mortal wounds are assigned. It is also an old warscroll, so GW being redundant about mortal wounds not allowing saves is a possibility.

 

[Aginor]

The description refers to normal saves. Rolls for avoiding mortal wounds are not "saves".
They also work differently because you save each wound separately.

So no, JLAST doesn't bypass them.