The Hammerfall Bunker is a Watch-fortress strongpoint dropped onto the battlefield — an armoured redoubt with an automated turret that anchors the Kill Team's firebase and holds the ground the strike withdraws to.
Place it as impassable terrain during set-up, in or beside the Deathwatch deployment zone. It grants full cover and a firing position: fighters inside gain +1 to Hit with ranged attacks and a 4+ save against incoming fire. Once per round, at the start of the Deathwatch turn, the bunker's turret makes a single ranged attack — treat it as a heavy bolter — against the nearest enemy in line of sight, taking the declared prey first if one is in range.