Griffin Aerie

At the beginning of your end step, if you gained 3 or more life this turn, create a 2/2 white Griffin creature token with flying.

Orzhov Basilica

Orzhov Basilica enters tapped.
When Orzhov Basilica enters, return a land you control to its owner's hand.
{T}: Add {W}{B}.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Soul Warden

Whenever another creature enters, you gain 1 life.

Counterspell

Karlov of the Ghost Council

Whenever you gain life, put two +1/+1 counters on Karlov of the Ghost Council.
{W}{B}, Remove six +1/+1 counters from Karlov of the Ghost Council: Exile target creature.

Exemplar of Light

Flying
Whenever you gain life, put a +1/+1 counter on this creature.
Whenever you put one or more +1/+1 counters on this creature, draw a card. This ability triggers only once each turn.

Will, Scion of Peace

Vigilance
{T}: Spells you cast this turn that are white and/or blue cost {X} less to cast, where X is the amount of life you gained this turn. Activate only as a sorcery.

Voice of the Blessed

Whenever you gain life, put a +1/+1 counter on Voice of the Blessed.
As long as Voice of the Blessed has four or more +1/+1 counters on it, it has flying and vigilance.
As long as Voice of the Blessed has ten or more +1/+1 counters on it, it has indestructible.

Essence Channeler

As long as you've lost life this turn, Essence Channeler has flying and vigilance.
Whenever you gain life, put a +1/+1 counter on Essence Channeler.
When Essence Channeler dies, put its counters on target creature you control.

Cleric Class

(Gain the next level as a sorcery to add its ability.)
If you would gain life, you gain that much life plus 1 instead.
{3}{W}: Level 2
Whenever you gain life, put a +1/+1 counter on target creature you control.
{4}{W}: Level 3
When this Class becomes level 3, return target creature card from your graveyard to the battlefield. You gain life equal to that creature's toughness.

Bolas's Citadel

You may look at the top card of your library any time.
You may play lands and cast spells from the top of your library. If you cast a spell this way, pay life equal to its mana value rather than pay its mana cost.
{T}, Sacrifice ten nonland permanents: Each opponent loses 10 life.

Oloro, Ageless Ascetic

At the beginning of your upkeep, you gain 2 life.
Whenever you gain life, you may pay {1}. If you do, draw a card and each opponent loses 1 life.
At the beginning of your upkeep, if Oloro, Ageless Ascetic is in the command zone, you gain 2 life.

Arcane Sanctum

Arcane Sanctum enters tapped.
{T}: Add {W}, {U}, or {B}.

Fountain of Renewal

At the beginning of your upkeep, you gain 1 life.
{3}, Sacrifice Fountain of Renewal: Draw a card.

Glacial Fortress

Glacial Fortress enters tapped unless you control a Plains or an Island.
{T}: Add {W} or {U}.

Dimir Signet

Sunken Hollow

({T}: Add {U} or {B}.)
Sunken Hollow enters tapped unless you control two or more basic lands.

Darksteel Mutation

Enchant creature
Enchanted creature is an Insect artifact creature with base power and toughness 0/1 and has indestructible, and it loses all other abilities, card types, and creature types.

Prairie Stream

({T}: Add {W} or {U}.)
Prairie Stream enters tapped unless you control two or more basic lands.

Swords to Plowshares

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

Sol Ring

Soul's Attendant

Whenever another creature enters, you may gain 1 life.

Command Tower

Enduring Tenacity

Whenever you gain life, target opponent loses that much life.
When Enduring Tenacity dies, if it was a creature, return it to the battlefield under its owner's control. It's an enchantment. (It's not a creature.)

Ajani's Welcome

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

Pearl Medallion

White spells you cast cost {1} less to cast.

Lunar Convocation

At the beginning of your end step, if you gained life this turn, each opponent loses 1 life.
At the beginning of your end step, if you gained and lost life this turn, create a 1/1 black Bat creature token with flying.
{1}{B}, Pay 2 life: Draw a card.