Belethurin

Lord of the woods: By howling it can make the jungle itself help you. attracting other beings from the recession or causing the flora to delay or attack your enemy

Spellcasting. The [Belethurin] is a 8-level spellcaster. Its spellcasting ability is [6] (spell save DC 6, +4 to hit with spell attacks). The [Belethurin] has following [druid] spells prepared:
Cantrips (at will): [control flames], [mold earth], [gust]
1st level ( 4 slots): [faerie fire], [Earth tremor], [Absorb elements], [Fog cloud]

2st level ( 3 slots): [Spike growth], [Pass without trace], [Gust of wind]

3st level ( 3 slots): [Dispel magic], [Erupting earth], [Call lightning]

4st level ( 2 slots): [Hallucinatory terrain], [Polymorph]

Multi attack. paws + bite 

Action paw Attack. Melee Weapon Attack: +9 to hit, reach 10 ft., 1 target. Hit: 2 (2d8 + 5) [slashing] damage. 

Action bite Attack. Melee Weapon Attack: +5 to hit, reach 5 ft., 1 target. Hit: 2 (2d12 + 3) [cold] damage.

Third eye dodge: Using it's raction the creature can reduce the damage recived by half and move 15ft in any direction as if it was dodging.

Once the monster health reaches 50% it will start using it"s legendary actions.

Reinforced fur (Costs 1 Actions). it's fur grows and gives the monster resistance to buldgeoning, piercing, and slashing from nonmagical attacks that aren't silverd for 1d6 minutes.

Legendary speed ( Costs 1 Actions). wind start to behave on the monter's will and give's it advantage on dex and cons save throws for the next 1d8 minutes