King of the Oathbreakers

Flying
Whenever King of the Oathbreakers or another Spirit you control becomes the target of a spell, it phases out. (Treat it and anything attached to it as though they don't exist until your next turn.)
Whenever King of the Oathbreakers or another Spirit you control phases in, create a tapped 1/1 white Spirit creature token with flying.

Dearly Departed

Flying
As long as Dearly Departed is in your graveyard, each Human creature you control enters with an additional +1/+1 counter on it.

Grey Host Reinforcements

Flying, ward {3}
When Grey Host Reinforcements enters, exile target player's graveyard. Put a number of +1/+1 counters on Grey Host Reinforcements equal to the number of creature cards exiled this way.

Andúril, Flame of the West

Equipped creature gets +3/+1.
Whenever equipped creature attacks, create two tapped 1/1 white Spirit creature tokens with flying. If that creature is legendary, instead create two of those tokens that are tapped and attacking.
Equip {2}

Anguished Unmaking

Exile target nonland permanent. You lose 3 life.

Banishing Light

When Banishing Light enters, exile target nonland permanent an opponent controls until Banishing Light leaves the battlefield.

Shadow Summoning

Create two tapped 1/1 white Spirit creature tokens with flying.

Soldier of the Grey Host

Flash
Flying
When Soldier of the Grey Host enters, target creature gets +2/+0 until end of turn.

Oath of the Grey Host

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — You and target opponent each create a Food token.
II — Each opponent loses 3 life. Create a Treasure token.
III — Create three tapped 1/1 white Spirit creature tokens with flying.

Fog on the Barrow-Downs

Enchant creature
Enchanted creature is a Spirit and can't attack or block. (It loses all other creature types.)

Bastion Protector

Commander creatures you control get +2/+2 and have indestructible.

Bitter Downfall

This spell costs {3} less to cast if it targets a creature that was dealt damage this turn.
Destroy target creature. Its controller loses 2 life.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Banish from Edoras

This spell costs {2} less to cast if it targets a tapped creature.
Exile target creature.