The Sister of Mercy is the deformed cultist who tried to pry Aiden away from the Genesis Configuration, and she turns up as Marlowe’s most devoted protector on the dance floor of his club. She fights almost entirely from the air, so the encounter punishes anyone who leaned on melee up to this point. Beating her is a matter of keeping fire on her, finishing her in the downed windows, and surviving three near-identical cycles.
Quick answer: Move to the raised walkway, set her alight with a Dragon’s Breath shotgun to stagger her, then switch to the Revolver for headshots. Knock her down three times, ripping her limbs off with Hell Chains, then execute her.
Loadout to bring before the fight starts
Stop at the merchant near the dance floor and stock up before triggering her. The Sister of Mercy spends most of the fight airborne, which means melee weapons barely connect and can leave you pinned at close range. Prioritize ranged options and fire damage.
- Shotgun with the Dragon’s Breath upgrade — sets her on fire, forcing her to panic and flail for several seconds.
- Revolver — low fire rate but very high single-target damage, ideal for landing critical headshots on a boss.
- An automatic weapon such as an SMG or AK-47 to pour damage in while she burns.
- Two medkits and bandages in any spare slots.
Ammo is plentiful during this encounter, so fire your automatic weapon liberally and check the breakable crates down in the blood if you run dry.
Position on the upper walkway
When the fight begins, climb onto the elevated levels that ring the dance floor. The floor itself floods with blood over the course of the battle, which heavily slows your movement and makes it a poor place to dodge her dives. The raised walkway keeps you mobile while still letting you drop down for the ammo crates below if needed.
Four large pillars stand around the room. Use them as cover against her ranged volleys, but keep in mind that her divebomb can split a column in two, so do not treat any single pillar as permanent protection.
Her attacks and how to counter them
Her two main moves are a divebomb that sends her rushing at you, and a projectile attack she launches after retreating into the air. For the projectiles, she conjures a cluster of knives and hurls them in waves. You can snatch these blades out of the air with the Genesis Configuration before they are thrown and fling them straight back at her.
She also holds those same blades as a shield that blocks some of your bullets. Shooting through it is possible but fiddly and wastes ammo, so clear the blades with the Genesis Configuration instead. The same ability lets you rip saws and spikes out of the environment and throw them for solid damage when you need an alternative to gunfire.
Working through the three knockdown cycles
The core loop repeats three times with small escalations each pass. Stick to the raised area, keep her burning, and time your shots.
After she has fallen twice, tear off her arms. Then use the Genesis Configuration to break pieces from the shield she raises around herself. Without her limbs, she has only ranged attacks; once the shield is broken, she is much easier to pin down and punish. In the later stage, she can encase herself in projectiles and launch them in a single powerful wave that can kill you in one hit, so smash the circling blades with objects you throw before she fires.
Do not try to clear the blood-flooded floor during the vanish phase. Cornering yourself on solid ground gives you a clear line on her silhouette and avoids getting slowed while she rushes in.
Execution, rewards, and what opens up
Defeat her repeatedly until she goes down for good, then execute her to kill her permanently. The execution animation confirms it, and the encounter ends. You receive the Sister of Mercy’s Heart to feed to Sunny, plus a valuable item that a merchant will buy for a few hundred coins. Her death unlocks the Labyrinth entrance behind the DJ booth, opening the route toward Marlowe.
