Celestial Unicorn

Whenever you gain life, put a +1/+1 counter on Celestial Unicorn.

Marauding Blight-Priest

Whenever you gain life, each opponent loses 1 life.

Soul's Attendant

Whenever another creature enters, you may gain 1 life.

Luminous Phantom

Flying
Whenever another creature you control leaves the battlefield, you gain 1 life.
If Luminous Phantom would be put into a graveyard from anywhere, exile it instead.

Lunarch Veteran

Whenever another creature you control enters, you gain 1 life.
Disturb {1}{W} (You may cast this card from your graveyard transformed for its disturb cost.)

Lunarch Veteran // Luminous Phantom

Soul Warden

Whenever another creature enters, you gain 1 life.