Shapechanger. The weredemon can use its action to polymorph into a demon-humanoid hybrid or into a demon, or back into its true form, which is humanoid. Its statistics, other than its AC, are the same in each form. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies.

Keen Hearing and Smell. The weredemon has advantage on Wisdom (Perception) checks that rely on hearing or smell.

Blood Transference. The Weredemon, unlike other Lycanthropes, does not spread it's curse by bite, but instead by creatures ingesting its blood. If ingested by choice the cursebearer controls when they change, if forced they change when commanded by another demon.

Multiattack. (Humanoid or Hybrid Form Only). The weredemon makes two attacks: two with its sword (humanoid form) or one with its bite and one with its claws (hybrid form).

Toxic Bite (Demon or Hybrid Form Only). Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 6 (1d8 + 3) piercing damage, and the target mus succeed on a DC 12 Constitution saving throw or take 7 (2d6) poison damage. 

Claws. (Demon or Hybrid Form Only). Melee Weapon Attack: +5 to hit, reach 5 ft., one creature. Hit: 7 (2d4 + 3) slashing damage.

Sword (Humanoid Form Only). Melee Weapon Attack: +5 to hit, reach 5ft., one creature. Hit: 7 (1d8 + 3) slashing damage, or 8 (1d10 + 3) slashing damage if used with two hands.