Some Wild Hunt ideas. I think Auberon is the best of the bunch, but they'd all help synergy with a pure WH deck.
Bronze:
Wild Hunt Slaver- The Wild Hunt was created first and foremost to collect slaves in other dimensions. This would be a 2 strength unit with the ability to lock and do 1 damage to a unit in frost.
Wild Hunt Wraith/Specter- During their raids, the Wild Hunt used vision projections to appear more spectral and intimidating. These would be 7 strength and gain 1 strength each round if frost is on the opposite side of the board.
Aen Elle Royal Cupbearer-Eredin had the former king of the Aen Elle assassinated via poison. These would be 5 strength and work the opposite of the Vrihedd Dragoons, damaging one random unit in an opponent's hand by 1 each round. Can't destroy a unit in this manner.
Aen Elle Unicorn Hunter-Before invading other realms, the Aen Elle had a war with unicorns in their realm (I cannot make this stuff up). These would be 5 strength, move a unit to this row on its side like the drowner, and damage it by 3. Increase damage dealt by 1 for each damaged enemy unit already on the row.
Silver:
Naglfar-Eredin's ship. This would have 9 strength with 2 armor. Start on a 1 turn cooldown, boosting all wild hunt units on your side of the board by 2 when activated. This is my Wild Hunt alernative to Iris, who it is currently almost impossible to play Eredin without due to the lack of high tempo options.
Apiarian Phantom-The named Wild Hunt Hound from the Witcher Contract. This would be 7 Strength and reset a unit. If that unit is under frost, reset a second unit.
Gold:
Auberon Muircetach - The King of the Aene Elle before he was assassinated by Eredin via poison. He would be 6 strength and spawn a poisoned cup (same effect as Foul Ale) into your opponent's hand.
Avallac'h (Wild Hunt)- Once an instrumental member of Eredin's inner circle, responsible for research into Elder blood and creating the Wild Hunt navigators. He would be a 4 strength spy and allow you to play one bronze Wild Hunt unit from your deck. Repeat this ability whenever a Wild Hunt Officer (Eredin, Caranthir, Ge'els, Nithral, Imlerith, Auberon, or Wild Hunt Geralt) is played.
Geralt (Wild Hunt)-Geralt rode with the Wild Hunt for years, described by Eredin as his best warrior. This would be 5 strength and reset a boosted unit, then damage another unit by the lost power.