Answered Prayers

Whenever a creature you control enters, you gain 1 life. If Answered Prayers isn't a creature, it becomes a 3/3 Angel creature with flying in addition to its other types until end of turn.

Guide of Souls

Whenever another creature you control enters, you gain 1 life and get {E} (an energy counter).
Whenever you attack, you may pay {E}{E}{E}. When you do, put two +1/+1 counters and a flying counter on target attacking creature. It becomes an Angel in addition to its other types.

Urborg, Tomb of Yawgmoth

Each land is a Swamp in addition to its other land types.

Plains

Karma

At the beginning of each player's upkeep, Karma deals damage to that player equal to the number of Swamps they control.

Lifecreed Duo

Flying
Whenever another creature you control enters, you gain 1 life.

Angelic Chorus

Whenever a creature you control enters, you gain life equal to its toughness.

Distinguished Conjurer

Whenever another creature you control enters, you gain 1 life.
{4}{W}, {T}: Exile another target creature you control, then return it to the battlefield under its owner's control.

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Soul's Attendant

Whenever another creature enters, you may gain 1 life.

Impassioned Orator

Whenever another creature you control enters, you 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

Divine Visitation

If one or more creature tokens would be created under your control, that many 4/4 white Angel creature tokens with flying and vigilance are created instead.

Kor Celebrant

Whenever Kor Celebrant or another creature you control enters, you gain 1 life.

Auriok Champion

Protection from black and from red
Whenever another creature enters, you may gain 1 life.

Soul Warden

Whenever another creature enters, you gain 1 life.

Anointer Priest

Whenever a creature token you control enters, you gain 1 life.
Embalm {3}{W} ({3}{W}, Exile this card from your graveyard: Create a token that's a copy of it, except it's a white Zombie Human Cleric with no mana cost. Embalm only as a sorcery.)

Daxos, Blessed by the Sun

Daxos's toughness is equal to your devotion to white. (Each {W} in the mana costs of permanents you control counts toward your devotion to white.)
Whenever another creature you control enters or dies, you gain 1 life.

Dingus Staff

Whenever a creature dies, Dingus Staff deals 2 damage to that creature's controller.

Kormus Bell

All Swamps are 1/1 black creatures that are still lands.

Bishop of Wings

Whenever an Angel you control enters, you gain 4 life.
Whenever an Angel you control dies, create a 1/1 white Spirit creature token with flying.

Healer of the Pride

Whenever another creature you control enters, you gain 2 life.

Angel

Darien, King of Kjeldor

Whenever you're dealt damage, you may create that many 1/1 white Soldier creature tokens.

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Ajani's Welcome

Whenever a creature you control enters, you gain 1 life.

Elephant

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.

Soldier

Generous Gift

Destroy target permanent. Its controller creates a 3/3 green Elephant creature token.

Blasting Station

{T}, Sacrifice a creature: Blasting Station deals 1 damage to any target.
Whenever a creature enters, you may untap Blasting Station.