Chocobo Necro Chicken (Draft)

Keen Sight and Smell. The Necro Chicken has advantage on Wisdom (Perception) checks that rely on sight or smell.

Pack Tactics. The Necro Chicken has advantage on an attack roll against a creature if at least one of the Necro Chicken's allies is within 5 feet of the creature and the ally isn't incapacitated. 

Undead Fortitude. If damage reduces the zombie chicken to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant or from a critical hit. On a success, the zombie chicken drops to 1 hit point instead.

Multiattack. The Necro Chicken makes two attacks: one with its beak and one with its talons. If it can it uses necrotic cloud.

Beak. Melee Weapon Attack: (Pro + Str to hit), reach 5 ft., one target. Hit: (2d4 + Str) piercing damage plus (3d6) necrotic damage. If the target is a creature, it must succeed on a DC (8+Pro+Con) Constitution saving throw or become diseased. A diseased creature, after a period of twenty-four hours has its strength reduced by 1d4 at the end of each hour and its max hit points by (3d6). The target dies and rots into a pile of slime if this reduces its Strength or maximum hit points to 0. If the disease is cured the strength and hit point reduction disappears.

Talons. Melee Weapon Attack: (Str to hit), reach 5 ft., one target. Hit: (2d6 + Str) slashing damage plus (1d6) necrotic damage.

Necrotic cloud (recharge 5-6). The Necro Chicken creates a 20-foot-radius sphere of poisonous, yellow-green fog centered on a point within 10 feet. The fog spreads around corners. It lasts for one minute or until strong wind disperses the fog, ending the effect. Its area is heavily obscured. When a creature enters the area for the first time on a turn or starts its turn there, that creature must make a DC (8+Pro+Con) Constitution saving throw. The creature takes (5d8) necrotic damage on a failed save, or half as much damage on a successful one. Creatures are affected even if they hold their breath or don't need to breathe. The fog moves 10 feet away from the vulture at the start of each of its turns, rolling along the surface of the ground. The vapors, being heavier than air, sink to the lowest level of the land, even pouring down openings.