Soul's Attendant

Whenever another creature enters, you may gain 1 life.

Soul Warden

Whenever another creature enters, you gain 1 life.

Thraben Inspector

When Thraben Inspector enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Radiant Fountain

When Radiant Fountain enters, you gain 2 life.
{T}: Add {C}.

Journey to Nowhere

When Journey to Nowhere enters, exile target creature.
When Journey to Nowhere leaves the battlefield, return the exiled card to the battlefield under its owner's control.

Suture Priest

Whenever another creature you control enters, you may gain 1 life.
Whenever a creature an opponent controls enters, you may have that player lose 1 life.

Battle Screech

Create two 1/1 white Bird creature tokens with flying.
Flashback—Tap three untapped white creatures you control. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Priest of Ancient Lore

When Priest of Ancient Lore enters, you gain 1 life and draw a card.

Quicksand

{T}: Add {C}.
{T}, Sacrifice Quicksand: Target attacking creature without flying gets -1/-2 until end of turn.

Plains

Celestial Unicorn

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

Squadron Hawk

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

Palace Sentinels

When Palace Sentinels enters, you become the monarch.

You Hear Something on Watch

Choose one —
• Rouse the Party — Creatures you control get +1/+1 until end of turn.
• Set Off Traps — This spell deals 5 damage to target attacking creature.