Shapechanger. The Werehouse can use its action to polymorph into a large house-humanoid hybrid or into a huge house, or back into its true form, which is humanoid. Its statistics, other than its size and AC, are the same in each form. Any equipment it is wearing or carrying isn't transformed, but kept inside. It reverts to a ruined house form if it dies.
Impassable. Except to exit, only allies can pass through the Werehouse’s squares. The werehouse allows (and encourages) exiting.
Multiattack. In house form, the werehouse makes one door attack and 2 window shutter attacks. In humanoid form, it makes two maul attacks. In hybrid form, it can make 1 door attack, 1 window attack, and one maul attack.
Crush (House or Hybrid Form Only). All enemies within the house must make DC 14 con save; on a fail they take (4d10+4) bashing damage or half damage on a save. Sleeping opponents are at disadvantage on the save.
Door (House or Hybrid Form Only). Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: (2d8 + 4) bashing damage.
Window shutter (House or Hybrid Form only). . Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: (1d8+4) bashing damage.
Maul (Humanoid or Hybrid Form Only). Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: (2d6+ 4) bashing damage.