Open the correct Red Room
Use the Brigand’s Sword on the barred door in the Manor Diner’s leftmost room. This is the normal Manor, not its Twilight version. Mutant has 100 base HP and Double Turns.
Elbow Grease → Rocket
The elbow-greasing animation applies Charged, Detachment and Fine, then ends the enemy turn. Reserve your next action for protection if you cannot guard Rocket. Ghost Potion costs 1 SP, with an Exhausted action afterward; restore HP before this window if necessary. Rocket is piercing but is not labelled unguardable like Azure Blast.
Mechanics references: Ghost Potion
Do not confuse the two Slams
Drain Slam has one slower wind-up and steals 20 HP. Triple Slam starts faster, hits three times for 7 each and delays the last hit. Stretch is another lifestealing punch, for 20 piercing damage. A missed lifesteal guard extends the fight by healing Mutant, so learn the wind-ups instead of adding only more raw damage.
The sequence and the reward
Drain Slam → Stretch → Triple Slam → Elbow Grease → Rocket → Barrage → Triple Slam. Barrage is a rapid six-hit move that can apply Dizzy. Winning gives the Manor Attic Key and Uncanny Encounter; the attic contains Slinger, Pack Tactics and Investor.