Soul Warden

Whenever another creature enters the battlefield, you gain 1 life.

Squadron Hawk

Flying
When Squadron Hawk enters the battlefield, you may search your library for up to three cards named Squadron Hawk, reveal them, put them into your hand, then shuffle.

Martyr of Sands

{1}, Reveal X white cards from your hand, Sacrifice Martyr of Sands: You gain three times X life.

Essence Warden

Soul's Attendant

Whenever another creature enters the battlefield, you may gain 1 life.