Vaitau

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

Mind Link. All the Guardians have a special mind link that connects them across the islands. They can communicate via this mind link as long as they are on the same plane.

Seasonal Aura. The Vaitau has a 10-foot radius aura. Each seasonal change (equinox or solstice), the Vaitau shifts to the new season, its color and aura changing. The following changes in the Vaitau's color and aura occur:

• Spring - The Vaitau changes to green, its aura becoming like a storm that inflicts 11 (2d10) lightning damage. 
• Summer - The Vaitau changes yellow. its aura becoming like fire that inflicts 11 (2d10) fire damage.
• Autumn - The Vaitau changes to brown, its aura becoming like wind that inflicts 11 (2d10) force damage. 
• Winter - The Vaitau changes to white, its aura becoming like ice that will inflict 11 (2d10) cold damage. 

Multiattack. The Vaitau makes two claw attacks. 

Claws Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) slashing damage.

Axis Tilt Tail Attack: The Vaitau targets up to 3 creatures in a 60-foot radius of itself. The creatures must pass a DC 18 Strength or Dexterity check (their choice) or be grappled.  Once they are grappled, the Vaitau can choose to throw them up to 60 feet away on subsequent turns. Any thrown creature will need to pass a DC 18 Dexterity saving throw or take 4d6 bludgeoning damage, taking half damage on a success.

Riua Protection of the Island Attack (Recharge on 5-6).  The Vaitau can create the Riua teleport ring. It can teleport any number of creatures that are a threat to its island. The Riua creates a 15-foot cube centered on any point Vaitau can see. All creatures with in the cube must make a DC 21 Dexterity saving throw, being sent to the town of Riua on the mainland on a fail.

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

Claws Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) slashing damage.

Tail Attack. +7 to hit, 15 ft., 19 (2d10+8) bludgeoning damage. Target must make a successful DC 19 Dexterity saving throw or be knocked prone. 

Seasonal Screech.  The Vaitau  releases an ear shattering Screech. All creatures in a 30-foot radius must make a DC 19 Constitution saving throw or take 19 (2d10+8) force damage become stunned. On a success, they take half damage are not stunned.