The following is a re-skinned variant of the Circle of Stars subclass, suitable for a Celtic / Brythonic themed Druid with an affinity to the otherworld of Annwn (ON-oon).
The strange Druids of this circle are in touch with the fabled Sunset Lands of Annwn, the realm of Arawn, home of the Wild Hunt, an abode of strange faerie beings and spirits of the dead.
You are able to perform a 1 hour ceremony to create a Silver Coin, a Tiny object you can use as a Spellcasting Focus for your Druid spells. While you carry your Silver Coin you have the Toll the Dead and Dissonant Whispers spells prepared. Additionally, you can cast Dissonant Whispers without expending a spell slot a number of times per Long Rest equal to your Wisdom modifier (minimum 1). When you cast Dissonant Whispers using this feature, the saving throw DC is increased by 1 and you can add your Wisdom bonus to the damage.
At the start of your turn, if you are not Incapacitated you can expend a use of your Wild Shape feature to take on your choice of one of the following Ankou Forms rather than shape-shifting.
While in your Ankou Form, you have Advantage on saving throws to avoid or end the Charmed and Frightened conditions. The form lasts for 10 minutes but ends early if you dismiss it (no action), become Incapacitated, or use this feature again.
Black Spear Bearer. While in this form you take on a reaper-like appearance and manifest a tenebrous black Spear. You can wield this Spear in the usual way, but it deals 1d10 Piercing or Necrotic damage (your choice), and you can use Wisdom as your attack attribute if you prefer.
Cauldron Born. While in this form you take on a waxy complexion and your eyes and mouth glow with a creepy green light (as does your blood, should it be shed). As a Bonus Action during your turn you may expend a spell slot to regain Hit Points equal to 1d8 + 2d8 per spell slot level.
Horned One. While in this form you sprout antler-like horns. When you make an Intelligence or Wisdom check or a Concentration save while in this form, you can treat a roll of 9 or lower on the d20 as a 10.
When you finish a Long Rest you can flip your Silver Coin. Roll a die to determine even or odd. Until you finish your next Long Rest, you gain access to the Weal Reaction if the roll is even or to the Woe Reaction if the roll is odd.
Whenever another creature you can see within 30 feet of you is about to make a d20 Test you can take a Reaction to modify the triggering d20 Test in the following way:
Weal (Even). The d20 Test is rolled with a +d6 bonus.
Woe (Odd). The d20 Test is rolled with a -d6 penalty.
Uses. You can use this Reaction a number of times per Long Rest equal to your Wisdom modifier (minimum 1).
Your Ankou Forms improve.
Black Spear Bearer. While in this form, the Spear's Thrown range improves to 150/600, and you may now make a ranged attack with it as a Bonus Action. If at the start of your turn you are not holding the Spear you may cause it to vanish and reform in your hand if it is empty.
Cauldron Born. While in this form, if you expend a spell slot to regain Hit Points you may now also move up to your Speed. This movement ignores Difficult Terrain and does not provoke Opportunity Attacks.
Horned One. While in this form you now have Advantage on saving throws to avoid or end the Stunned, Paralyzed, and Restrained conditions.
While in your Ankou Form, you become nearly indestructible. You reduce all damage by an amount equal to your Wisdom modifier (minimum 1) and you gain the benefits of the Death Ward spell. However, your Ankou Form ends if the Death Ward is triggered.