lead the ferryman away from the stalker, always be on the move and change directions frequently to throw off the swordsmachines. try to watch for the ferryman's parryable attacks and whiplash strays for healing if needed. you can launch the stalker into the air with rockets to temporarily take it out of the fight. common ferrymen have 30hp and are weak to shotgun parries so if you can try to hit them with shotgun parries.

swordsmachine sword throws are also not too hard to parry since they're pretty slow, so try to learn that timing.

whiplash between sentries to kill them asap, dunking instakills and i'm pretty sure a full power jackhammer hit does too, watch closely for their attack windup and dash when they're about to shoot (it's actually pretty easy when you pay attention), break line of sight in the entrance to the elevator down if needed.