COPY_OF_Nettleem, Mischiveous God of Festivals and Magic

False Appearance. While the treant remains motionless, it is indistinguishable from a normal tree.

Innate Spellcasting. Nettleem's Spellcasting Ability is Intelligence (Spell Save DC 26). He can cast the following spells as an action, ignoring any verbal, somatic, or material components. 
At Will. Cause Fear (3rd Level), Ice Knife (3rd Level), Misty Step, Major Illusion. 
2/Day. Freezing Sphere, Wall of Thorns, Draconic Transformation (only on an Animated Tree). 
1/ Day. Illusionary Dragon (in the shape of himself, he becomes invisible to all who fail a perception/investigation check), Storm of Vengeance. 

Legendary Resistance (5/Day)

Felled Mischief. If Nettleem would be reduced to 0 hit points, his current hit points instead resets to 500. After using this feature, a menacing, purple aura exudes from his body. If a creature ends it's turn within 10ft of Nettleem, they must make a Wisdom saving throw (DC 18) or be frightened for 30 seconds. Additionally, Nettleem can use options from the Mythic Actions table for an hour following the use of this feature. 

Magic Resistance. Nettleem has advantage on all saving throws on magical effects. 

Magical Weapons. Nettleem's Weapon attacks are all considered magical. 

Regeneration. Nettleem regains 30 hit points at the start of each of it's turns. 

Siege Monster. The treant deals double damage to objects and structures.

Multiattack. Nettleem makes two slam attacks. 

Slam. Melee Weapon Attack: +18 to hit, reach 10 ft., one target. Hit: 36 (6d6 + 10) bludgeoning damage.

Animate Trees (6/Day). The treant magically animates one or two trees it can see within 60 feet of it. These trees have the same statistics as a treant, except they have Intelligence and Charisma scores of 1, they can't speak, and they have only the Slam action option. An animated tree acts as an ally of the treant. The tree remains animate for 1 day or until it dies; until the treant dies or is more than 120 feet from the tree; or until the treant takes a bonus action to turn it back into an inanimate tree. The tree then takes root if possible.

Nettleem can take one reaction per round. 

Dreadful Counterspell (4/day). Nettleem utters a dreadful word that interrupts a spellcaster that he can see from casting a spell. If the spell is 4th level or lower, it fails and has no effect. If the spell is 5th level or higher, Nettleem makes an intelligence check (DC 10 + the spells level). On a success, the spell fails and has no effect. 

Nettleem can make 5 Legendary Actions per round at the end of another creature's turn. These Legendary Actions refresh at the end of his turn. 

Slam (Costs 2 Actions). Nettleem makes a slam attack. 

Animate Tree (Costs 2 Actions). Nettleem animates one tree. 

Cast a Spell (Costs 3 Actions). Nettleem casts a spell of 7th level or lower. 

If the Felled Mischief feature has been activated in the last hour, Nettleem can use the following actions as Legendary Actions.

Enraged Dash (Costs 3 Actions). Nettleem dashes at full speed at an enemy within his sight, that is on the same plane as him. The creature must make a Dexterity saving throw, DC 18. On a success, the creature successfully dodges his charge. On a failed save, the creature is thrown 30 feet back, knocked prone, and takes 5d10 bludgeoning damage.

Astral Stump (Costs 5 Actions). Nettleem makes a slam attack with an astral stump on a creature within his sight, on the same plane as him, within 120 feet. If the creature is engaged with another creature, or has any negative effects on it, any hit with this stump is treated as a critical hit.