Archgriffon

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

Keen Mind. The archgriffon has attributes of the Keen Mind feat. It always knows which way is north and how many hours before the next sunrise or sunset, and can accurately recall anything it has seen or heard within the past month.

Legendary Resistance (1/day). If the archgriffon fails a saving throw, it can choose to succeed instead.

Adrenaline Shock. If the archgriffon becomes blinded, deafened, or restrained, or takes damage while it has fewer than 100 hit points, it immediately gains (4d8) temporary hit points and the effects of Haste for 1 minute. The effects are physiological, and therefore cannot be magically dispelled. Its speed is doubled, it gains a +2 bonus to AC, it has advantage on Dexterity saving throws, and it gains an additional action on each of its turns. The effect ends early if the archgriffon starts its turn incapacitated. When the effect ends, the archgriffon takes 1 point of exhaustion.

Multiattack. The griffon makes two attacks: one with its beak and one with its talons.

Beak. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: (3d8 + 4) slashing damage.

Talons. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: (2d6 + 4) piercing damage.

Maul. The archgriffon may make a contested Strength or Dexterity throw (target's choice) with a prone creature it has grappled, losing ties. If the archgriffon succeeds, it may immediately move or fly up to half its movement speed with the grappled creature and then make one attack against the same creature as a bonus action. If the grappled creature takes damage from this attack, all creatures within 30 feet must make a DC 12 Wisdom saving throw or become frightened for one round. If the creature is reduced to 0 HP, it is brutally dismembered and all creatures within 60 feet must make a DC 16 Wisdom saving throw or become frightened for one minute.

Onslaught. If the archgriffon has dealt damage to a single creature with two claw attacks since that creature's last turn, the archgriffon may grapple that creature as a bonus action. If successful, the target creature is knocked prone and becomes grappled.

The archgriffon can take 2 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 archgriffon regains spent legendary actions at the start of its turn.

Talons. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: (2d6 + 4) piercing damage.

Assail. The archgriffon aggressively snaps its beak and beats its wings at a creature within 5 ft. of it. The target creature must succeed a contested Dexterity check, winning ties, or is shoved 5 ft. away from the archgriffon and takes (1d6) bludgeoning damage. If there is no space to move, it is instead knocked prone.

Wing Flash (Costs 2 actions). The archgriffon thrusts its wings forward and violently fans them in a disorienting display, breaking the concentration of any creature within 10 ft. On its next turn, the archgryphon may move up to half its speed without provoking any opportunity attacks.