Beasts blood: If damage reduces the yharnamite to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is fire, radiant or necrotic or from a critical hit. On a success, the yharnamite drops to 1 hit point instead.

Each monster can only use one type of weapon attack.

Slam. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 4 (1d6 + 1) bludgeoning damage.

Hatchet  melee weapon attack +3 to hit reach 5ft, one target Hit 5 (1d6+2) slashing damage 

Pitchfork melee weapon attack +4 to hit reach 10ft, one target Hit 6(1d6+2) piercing damage