Boss Delour

If Delour is subjected to an effect that allows him to make a Dexterity saving throw to take only half damage, he instead takes no damage if he succeeds on the saving throw and only half damage if he fails, provided he doesn't have the Incapacitated condition.

Delour can move through the space of a Medium or larger creature.

Delour regains 10 hit points at the start of his turn. If he takes damage from a silver weapon, this trait doesn't function at the start of his next turn. Delour dies only if he starts his turn with 0 hit points and doesn't regenerate.

Delour makes any combination of three Bite, Shortsword, or Hand Crossbow attacks.

Melee Weapon Attack +8 to hit, reach 5 ft., one target. 26 (5d8 + 4) Piercing damage. If the target is a Humanoid, it must succeed on a DC 14 Constitution saving throw or be cursed with lycanthropy. While cursed in this way, the target retains its alignment, languages, and equipment but otherwise uses the wererat stat block, excluding actions that require equipment the target doesn't have. During any night when there's a full moon in the sky, the target becomes an NPC under the DM's control and remains so until the night ends. A Remove Curse spell or similar magic ends this curse.

Melee Weapon Attack +8 to hit, reach 5 ft., one target. 11 (2d6 + 4) Piercing damage plus 10 (3d6) Poison damage.

Ranged Weapon Attack +8 to hit, range 30/120 ft., one target. 11 (2d6 + 4) Piercing damage plus 10 (3d6) Poison damage.

Delour polymorphs into a rat-humanoid hybrid, a Medium giant rat, or his humanoid form. His statistics, other than his size and speed, are the same in each form. Any equipment he is wearing or carrying isn't transformed. He reverts to his humanoid form if he dies.

Delour takes the Dash, Disengage, or Hide action.