Summoned into her hands while she is lying on top of a boss, and fired straight down into its back.
On the run to the trainyard Katia Grim sets up at the back of the Interdiction Rapid-Response Railway Repair Cart facing backward, ready to shoot anything that gives chase. In the tunnel ambush she stays lying across the pinned ManTauR while the crossbow appears in her hands and starts pumping bolts into him at contact range — the boss scrabbling at the rock with his claws underneath her the whole time.
A heavy repeating crossbow that manifests in her hands as needed.
Katia's ranged weapon, used here as a point-blank finisher.