Eight/Realmbreaker. Wrenn has bonded with the legendary tree Realmbreaker, renaming it "Eight". They are joined through mind, body & soul. Eight/Realmbreaker acts as additional limbs for Wrenn, including her legs. Without Eight/Realmbreaker, Wrenn would slowly die if she cannot bond with another tree. If they choose so, a creature can directly attack Eight/Realmbreaker instead of Wrenn. Eight/Realmbreaker has AC 22 and 200 Hit Points. Wrenn will protect Eight/Realmbreaker and prioritise healing her bonded tree at the expense of her own safety

Legendary Resistance (3/day). If Wrenn & Eight fails a saving throw, she can choose to succeed.

Magic Weapons. Wrenn & Eight's attacks are considered magical.

War Caster. Wrenn & Eight can use her reaction to cast a spell with a casting time of 1 action against a creature that leaves her melee range.

Spellcasting. Wrenn & Eight is a 16th-level spellcaster. Her spellcasting ability is Wisdom (spell save DC 18, +12 to hit with spell attacks). Wrenn & Eight has following Druid spells prepared:
Cantrips (at will): Druidcraft, Primal Savagery, Thornwhip
1st level (5 slots): Cure Wounds, Entangle, Thunderwave

2nd level (5 slots): Enlarge/Reduce, Heat Metal, Hold Person, Moonbeam

3rd level (4 slots): Dispel Magic, Speak With Plants, Tidal Wave

4th level (4 slots): Blight, Ice Storm, Polymorph

5th level (3 slots): Conjure Elemental, Wrath of Nature

6th level (2 slots): Heal, Sunbeam

7th level (1 slot): Fire Storm

Multiattack. Wrenn & Eight can cast a spell. She then makes two attacks with her claws. 

Claw Attack. Melee Weapon Attack: +11 to hit, reach 10 ft., 1 target. Hit:  20 (4d8 + 8) slashing damage. 

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Opportunity Attack. Wrenn & Eight can use her reaction to cast a spell with a casting time of 1 action against a creature that leaves her melee range.

Wrenn & Eight 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. Wrenn & Eight regains spent legendary actions at the start of her turn.

Claw Attack (Costs 1 Action). Wrenn & Eight makes a claw attack

Cast a Spell (Costs 1 Action). Wrenn & Eight can cast a spell of third level or lower

Realmbreaker (Costs 3 Actions). Wrenn & Eight unleashes the full might of her bonded tree, Realmbreaker. Each creature within 30 feet of Wrenn & Eight must make a DC 18 Intelligence Saving Throw, taking 6d10 Force damage on a failed save, or half as much on a success. A creature that fails the save is also stunned until the end of their next turn

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Mythic Action Name (Costs # Actions). Enter the description for your mythic action.