Avatar of Basti

Tough Skin.  When the Avatar of Basti takes damage, it's crocodilian skin hardens to cover its entire body. It gains resistance to that damage type until the start of it's next turn. If the Avatar is already resistant, it gains immunity.

Night Predator. While the Avatar of Basti is not incapacitated, it produces a 10-foot radius aura of magical darkness centered on itself. This aura can be dispelled with magical light from spells of 5-th level or higher; and from magic items of Very Rare or higher rarity.

Regeneration. The Avatar of Basti regains 10 hit points at the start of its turn. If the Avatar of Basti takes cold damage or is immersed in water, this trait doesn’t function at the start of the Avatar of Basti's next turn. The Avatar of Basti dies only if it starts its turn with 0 hit points and doesn’t regenerate.

Limited Magic Immunity. Avatar of Basti can’t be affected or detected by spells of 5th level or lower unless it wishes to be. It has advantage on saving throws against all other spells and magical effects.

Pyroclasm. At the start of each of the Avatar of Basti's turns, Gouts of molten lava erupt from the Avatar of Basti's body, permanently coating the ground in a 5-foot-radius sphere centered on the Avatar of Basti. Any creature in the area must make a DC 15 Dexterity saving throw. On a failed saving throw, a creature takes 21 (6d6) fire damage. On a successful saving throw, a creature must use its reaction to move 5 feet away from the Avatar of Basti. A creature that has no reactions automatically fails the save.

Lava Pool. When a creature enters the lava-coated area for the first time on a turn or starts its turn there it must make a DC 15 constitution saving throw. On a failed saving throw, a creature takes 21 (6d6) fire damage. The lava pool can be extinguished with water. An extinguished area becomes heavily obscured for 1 round.

Multiattack. The Avatar of Basti leaps up to 10 feet without provoking attacks of opportunity, then makes one Lunging Bite attack and one Tail attack.

Lunging Bite. Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 24 (3d10 + 7) magical piercing.

Tail. Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 14 (1d12 + 7) bludgeoning damage. If the target is a Large or smaller creature, it must succeed on a DC 19 Strength saving throw or be knocked prone.

The Avatar of Basti can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature’s turn. The Avatar of Basti regains spent legendary actions at the start of its turn.

Lunging Bite. The Avatar of Basti makes one Lunging Bite attack.

Shadow Leap. The Avatar of Basti teleports, along with any equipment it is wearing or carrying and any creatures it has grappled, up to 60 feet to an unoccupied space that is not brightly lit or is obscured.

Consume Force (3 actions). The Avatar of Basti touches a creation of magical force within 5 feet of it. That creation is immediately destroyed. The Avatar of Basti immediately takes force damage equal to 10 x the level of the spell used to create the force object, or 52 (8d12) force damage.