Soul Warden

Whenever another creature enters, you gain 1 life.

Swamp

Mana Tithe

Counter target spell unless its controller pays {1}.

Plains

Momentary Blink

Exile target creature you control, then return it to the battlefield under its owner's control.
Flashback {3}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Chittering Rats

When Chittering Rats enters, target opponent puts a card from their hand on top of their library.

Phyrexian Rager

When Phyrexian Rager enters, you draw a card and you lose 1 life.

Sanguine Indulgence

This spell costs {3} less to cast if you've gained 3 or more life this turn.
Return up to two target creature cards from your graveyard to your hand.

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.

Scoured Barrens

Scoured Barrens enters tapped.
When Scoured Barrens enters, you gain 1 life.
{T}: Add {W} or {B}.

Thraben Inspector

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

Ninth Bridge Patrol

Whenever another creature you control leaves the battlefield, put a +1/+1 counter on Ninth Bridge Patrol.

Radiant Fountain

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

Burglar Rat

When Burglar Rat enters, each opponent discards a card.

Soul's Attendant

Whenever another creature enters, you may gain 1 life.

Epicure of Blood

Whenever you gain life, each opponent loses 1 life.

Ephemerate

Exile target creature you control, then return it to the battlefield under its owner's control.
Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)

Skymarch Bloodletter

Flying
When Skymarch Bloodletter enters, target opponent loses 1 life and you gain 1 life.

Unmake

Castigate

Target opponent reveals their hand. You choose a nonland card from it and exile that card.