Detect Invisibility. The King of Feathers can see invisible creatures and objects as if they were visible.

Legendary Resistance (3/Day). If the King of Feathers fails a saving throw, it can choose to succeed instead.

Innate Spellcasting. The King of Feathers's innate spellcasting ability is Wisdom. It can innately cast the following spell, requiring no material components:

At will: misty step

Multiattack. The King of Feathers makes two attacks: one with its bite and one with its tail. It can't make both attacks against the same target.

Bite. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit:33 (4d12 + 7) piercing damage. If the target is a Medium or smaller creature, it is grappled (escape DC 17). Until this grapple ends, the target is restrained, and the tyrannosaurus can't bite another target.

Tail. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit:20 (3d8 + 7) bludgeoning damage.

Summon Swarm (Recharge 5–6). The King of Feathers exhales a swarm of insects (wasps) that forms in a space within 20 feet of it. The swarm acts as an ally of the King of Feathers and takes its turn immediately after it. The swarm disperses after 1 minute. It can't use the Summon Swarm action while it is grappling a creature with its jaws.