oh my loving god i called this and still nobody loving cares that they're impervious to fire
jesus christ the solution to everything isn't just "fire and hope they die"
run for chrissakes. if you get a chance double back and pick up the artifact, but if you do so have two guys go do it because sending one may end up having him getting hypnotized or whatever like tom (?) on the ship.
as for Ulris, if you can't pick him up and run away fast enough you'll have to leave him to die. Either way he should continue firing even though its not going to do anything, as the bullets will at the very least distract them.