Bastille Agent

Devil's Sight. Magical darkness doesn't impede the agent's darkvision.

Legendary Resistance (3/Day). If the agent fails a saving throw, they can choose to succeed instead.

Magic Resistance. The agent has advantage on saving throws against spells and other magical effects.

Iron Wings. The bastille agent has half cover from ranged attacks, using its wings to deflect incoming attacks.

Multiattack. The bastille agent makes three melee attacks: two with its fork and one with its tail. It can use Hurl Flame in place of any melee attack.

Fork. Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: 15 (2d8 + 6) piercing damage.

Tail. Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: 10 (1d8 + 6) piercing damage. If the target is a creature other than an undead or a construct, it must succeed on a DC 17 Constitution saving throw or lose 10 (3d6) hit points at the start of each of its turns due to an infernal wound. Each time the bastille agent hits the wounded target with this attack, the damage dealt by the wound increases by 10 (3d6). Any creature can take an action to stanch the wound with a successful DC 12 Wisdom (Medicine) check. The wound also closes if the target receives magical healing.

Hurl Flame. Ranged Spell Attack: +9 to hit, range 150 ft., one target. Hit: 14 (4d6) fire damage. If the target is a flammable object that isn't being worn or carried, it also catches fire.

Spellcasting. The bastille agent casts one of the following spells, requiring no material components and using Charisma as the spellcasting ability (spell save DC 17):

2/day each: cone of cold, darkness, fireball, lightning bolt, stinking cloud

Deflect. When the bastille agent is hit with an attack, it can use its reaction to deflect the attack, granting itself a +3 to his AC against the triggering attack. If the attack misses and was a ranged attack, the attack is reflected back at a random creature within 30 feet of the agent.  The agent can not use this trait if its Iron Dome ability is active.

The bastille agent can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The agent regains spent legendary actions at the start of its turn.

Fork. The bastille agent makes a fork attack.

Cast a Spell (Costs 2 Actions). The bastille agent casts a spell.

Iron Dome (Costs 3 Actions). The bastille agent encases itself in its wings granting itself 3/4 cover, resistance to all damage, and advantage on Constitution saving throws until the start of it's next turn.  It can also move up to half it's movement speed.  If a ranged attack misses the agent while it is within it's Iron Dome, the attack is reflected back at a random creature within 30 feet of the agent.