Thunderbird

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

Storm Sight. A thunderbirds vision is not limited by weather.

Multiattack. The griffon attacks once with its beak and once with its talons.

Beak. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 9 (2d4 + 4) piercing damage.

Talons. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 7 (1d6 + 4) slashing damage or 11 (2d6 + 4) slashing damage if the griffon started its turn at least 20 feet above the target and the target is grappled (escape DC 14). Until this grapple ends the griffon can't attack a different target with its talons.

Lightning Strike (Recharge 6). The thunderbird exhales a blast of lightning at one target within 60 feet. The target makes a DC 12 Dexterity saving throw taking 28 (8d6) lightning damage on a failure or half the damage on a success.