Spellcasting. The archdruid is an 18th-level spellcaster. Its spellcasting ability is Wisdom (spell save DC 17, +9 to hit with spell attacks). It has the following druid spells prepared:

Cantrips (at will): druidcraft, mending, poison spray, produce flame

1st level (4 slots): cure wounds, entangle, faerie fire, speak with animals, Fortune's Favor

2nd level (3 slots): animal messenger, beast sense, hold person

3rd level (3 slots): conjure animals, meld into stone, water breathing

4th level (3 slots): dominate beast, locate creature, stoneskin, wall of fire

5th level (3 slots): commune with nature, mass cure wounds, tree stride, temporal shunt

6th level (1 slot): heal, heroes’ feast, sunbeam

7th level (1 slot): fire storm, tether essence

8th level (1 slot): animal shapes

9th level (1 slot): foresight

Star Map
Circle of the Stars feature

You've created a star map as part of your study of the heavens. The map is a Tiny object and can serve as a spellcasting focus for your druid spells. You decide what form the object takes, or you can determine what it is by rolling on the Star Map table.

If you lose your map, you can perform a 1-hour ceremony to magically create a replacement. This ceremony can be performed during a short or long rest, and it destroys the previous map. You can cast the augury and guiding bolt spells without expending a spell slot and without preparing the spell, provided you use the star map as the spellcasting focus. You can cast a spell from the map in this way a number of times equal to your Wisdom modifier (minimum of once), and you regain all expended uses when you finish a long rest

Starry Form
Circle of Stars Feature

You gain the ability to harness constellations’ power to alter your form. As an action, you can expend a use of your Wild Shape feature to take on a starry form rather than transforming into a beast. While in your starry form, you retain your game statistics, but your body takes on a luminous, starlike quality; your joints glimmer like stars, and glowing lines connect them as on a star chart. This form sheds bright light in a 10- foot radius and dim light for an additional 10 feet. The form lasts for 10 minutes or until you’re incapacitated. Whenever you assume your starry form, choose which of the following constellations glimmers on your body; your choice gives you certain benefits while in the form:
Chalice: A constellation of a life-giving goblet appears on you. Whenever you cast a spell using a spell slot that restores hit points to a creature, you or another creature within 30 feet of you can regain hit points equal to 1d8 + half your level in this class.
Archer: A constellation of an archer appears on you. You gain a bonus action that you can use to make a ranged spell attack, hurling a luminous arrow that targets a creature you can see within 60 feet of you. On a hit, the attack deals radiant damage equal to 1d8 + your Wisdom modifier.
Dragon: A constellation of a wise, ancient dragon appears on you. When you make an Intelligence or a Wisdom check or a Constitution saving throw to maintain concentration on a spell, you can treat a roll of 9 or lower on the d20 as a 10.

Cosmic Omen
Circle of the Stars feature

You learn to use your star map to divine the will of the cosmos. Whenever you finish a long rest, you can consult your star map for omens. When you do so, roll a d6. You gain one of the following possible omens based on whether you rolled an even number or an odd number on the d6: Weal (even). Whenever a creature you can see within 30 feet of you makes an attack roll, a saving throw, or an ability check, you can use your reaction to roll a d6 and add the number rolled to the total. Woe (odd). Whenever a creature you can see within 30 feet of you makes an attack roll, a saving throw, or an ability check, you can use your reaction to roll a d6 and subtract the number rolled from the total. You can use this reaction a number of times equal to your Wisdom modifier, and you regain all expended uses when you finish a long rest.

 Hapless: Ygrid has disadvantage on Charisma-based skill checks. 

Scimitar. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 5 (1d6 + 2) slashing damage.

Change Shape (2/Day). The archdruid magically polymorphs into a beast or elemental with a challenge rating of 6 or less, and can remain in this form for up to 9 hours. The archdruid can choose whether its equipment falls to the ground, melds with its new form, or is worn by the new form. The archdruid reverts to its true form if it dies or falls unconscious. The archdruid can revert to its true form using a bonus action on its turn.

While in a new form, the archdruid retains its game statistics and ability to speak, but its AC, movement modes, Strength, and Dexterity are replaced by those of the new form, and it gains any special senses, proficiencies, traits, actions, and reactions (except class features, legendary actions, and lair actions) that the new form has but that it lacks. It can cast its spells with verbal or somatic components in its new form.

The new form’s attacks count as magical for the purpose of overcoming resistances and immunity to nonmagical attacks.