Ankshar

Gaze of rage. Up to three creatures the ankshar chooses on the start of the ankshar's turn must make a dc 16 Charisma save or be forced to loss concentration on any spells and be aggressive and lash out and attack any creatures that deal any damage to the creature or if they are not damaged before their turn the creature must find a way to make a weapon attack against the nearest creature. 

Compact body. The ankshar retracts or extends its wings or two of its legs as half its movement action. Whilst its wings and legs are retracted the ankshar's size is reduced to medium (reach is unaffected by this ). In this form it can't fly or use its wings to attack but it gains proficiency in stealth checks. 

Magic resistance. The ankshar has advantage on saving throws against spells and other magical effects.

Multi attack. The ankshar makes one bite attack, two wing attacks, one gore attacks and a tail attack. 

Bite. Melee Weapon Attack: +9 to hit, reach 5 ft., 1 target. Hit: 10 (1d8 + 6) piercing damage and the target must make a dc 16 Constitution saving throw or be super naturally diseased. Whilst diseased in this way the creature's dexterity is reduced by 2d4 and when being healed they only heal 1/2 of the amount they should heal (this includes long rests).

Wing. Melee Weapon Attack: +9 to hit, reach 10 ft., 1 target. Hit: 9 (1d6 + 6) bludgeoning damage. 

Gore. Melee Weapon Attack: +9 to hit, reach 5 ft., 1 target. Hit: 12 (1d12 + 6) piercing damage. 

Tail. Melee Weapon Attack: +3 to hit, reach 10 ft., 1 target. Hit: 4 (1d8) Bludgeoning damage and the target must make a dc 16 Strength save or be knocked prone.