Homebrew
Survivor. Any damage which reduces the hit points of the tenebrac below 1 hit point, reduces their hit points to 1 instead. Does not apply if the tenebrac has only 1 hit point.
Multiattack. The tenebrac makes two claw attacks. Poisonous Claw. Melee Weapon Attack: +5 to hit, reach 1 sq., one target. Hit: 6 ( 1d6+3 ) slashing damage and applies a weak paralyzing posion (Constitution saving throw DC 5). When poisoned the victim is paralyzed for two rounds.
Underdark