Apex Griffon Monarch

Keen Sight. The griffon has advantage on Wisdom (Perception) checks that rely on sight.

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

Legendary Resistance (2/Day). If the griffon fails a saving throw, it can choose to succeed instead.

Dive. If the griffon moves at least 30 feet straight down while flying towards a creature and then hits it with a claw attack on the same turn, that target must succeed on a DC 22 Strength saving throw or be knocked prone. If the target is prone, the griffon can make one beak attack against it as a bonus action.

Multiattack. The griffon can use its Frightful Presence. It then makes three attacks: one with its beak and two with its claws. 

Beak. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 19 (2d10 + 8) piercing damage plus 6 (2d6) fire damage.

Claw. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 15 (2d6 + 8) slashing damage.

Frightful Presence. Each creature of the griffon's choice that is within 120 feet of the griffon and aware of it must succeed on a DC 18 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the griffon's Frightful Presence for the next 24 hours.

Breath (Recharge 5–6). The griffon exhales breath in a 90-foot cone. Each creature in that area must make a DC 21 Dexterity saving throw, taking 56 (16d6) damage on a failed save, or half as much damage on a successful one.

The griffon 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 griffon regains spent legendary actions at the start of its turn.

Detect. The griffon makes a Wisdom (Perception) check.

Wing Attack (Costs 2 Actions). The griffon beats its wings. Each creature within 15 feet of the griffon must succeed on a DC 22 Dexterity saving throw or take 15 (2d6 + 8) bludgeoning damage and be knocked prone. The griffon can then fly up to half its flying speed.