Sunbond

Enchant creature
Enchanted creature has "Whenever you gain life, put that many +1/+1 counters on this creature."

Rune-Tail's Essence

Prevent all damage that would be dealt to creatures you control.

Rune-Tail, Kitsune Ascendant

When you have 30 or more life, flip Rune-Tail.

Rune-Tail, Kitsune Ascendant // Rune-Tail's Essence

Storm Herd

Create X 1/1 white Pegasus creature tokens with flying, where X is your life total.

Evra, Halcyon Witness

Lifelink
{4}: Exchange your life total with Evra's power.

Linden, the Steadfast Queen

Vigilance (Attacking doesn't cause this creature to tap.)
Whenever a white creature you control attacks, you gain 1 life.

Sunscorch Regent

Flying
Whenever an opponent casts a spell, put a +1/+1 counter on this creature and you gain 1 life.

Werefox Bodyguard

Flash
When this creature enters, exile up to one other target non-Fox creature until this creature leaves the battlefield.
{1}{W}, Sacrifice this creature: You gain 2 life.

Comeuppance

Prevent all damage that would be dealt to you and planeswalkers you control this turn by sources you don't control. If damage from a creature source is prevented this way, Comeuppance deals that much damage to that creature. If damage from a noncreature source is prevented this way, Comeuppance deals that much damage to the source's controller.

Eight-and-a-Half-Tails

{1}{W}: Target permanent you control gains protection from white until end of turn.
{1}: Target spell or permanent becomes white until end of turn.

Filigree Familiar

When this creature enters, you gain 2 life.
When this creature dies, draw a card.

Heliod, Sun-Crowned

Indestructible
As long as your devotion to white is less than five, Heliod isn't a creature.
Whenever you gain life, put a +1/+1 counter on target creature or enchantment you control.
{1}{W}: Another target creature gains lifelink until end of turn.

Archangel of Thune

Flying
Lifelink (Damage dealt by this creature also causes you to gain that much life.)
Whenever you gain life, put a +1/+1 counter on each creature you control.

Patron of the Kitsune

Fox offering (You may cast this spell any time you could cast an instant by sacrificing a Fox and paying the difference in mana costs between this and the sacrificed Fox. Mana cost includes color.)
Whenever a creature attacks, you may gain 1 life.

Serra Avatar

Serra Avatar's power and toughness are each equal to your life total.
When Serra Avatar is put into a graveyard from anywhere, shuffle it into its owner's library.

Twinblade Paladin

Whenever you gain life, put a +1/+1 counter on this creature.
As long as you have 25 or more life, this creature has double strike. (It deals both first-strike and regular combat damage.)

Clockwork Fox

When this creature leaves the battlefield, you draw two cards and each opponent draws a card.

Ajani's Pridemate

Whenever you gain life, put a +1/+1 counter on this creature.

Farfinder

Vigilance
When this creature enters, you may search your library for a basic land card, reveal it, put it into your hand, then shuffle.

Field-Tested Frying Pan

When this Equipment enters, create a Food token, then create a 1/1 white Halfling creature token and attach this Equipment to it.
Equipped creature has "Whenever you gain life, this creature gets +X/+X until end of turn, where X is the amount of life you gained."
Equip {2}

Sol Ring

Cosmos Elixir

At the beginning of your end step, draw a card if your life total is greater than your starting life total. Otherwise, you gain 2 life.

Soul's Attendant

Whenever another creature enters, you may gain 1 life.

Regna, the Redeemer

Partner with Krav, the Unredeemed (When this creature enters, target player may put Krav into their hand from their library, then shuffle.)
Flying
At the beginning of each end step, if your team gained life this turn, create two 1/1 white Warrior creature tokens.

Light of Promise

Voice of the Blessed

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

Celestial Unicorn

Soul Warden

Whenever another creature enters, you gain 1 life.

Ajani, Strength of the Pride

+1: You gain life equal to the number of creatures you control plus the number of planeswalkers you control.
−2: Create a 2/2 white Cat Soldier creature token named Ajani's Pridemate with "Whenever you gain life, put a +1/+1 counter on Ajani's Pridemate."
0: If you have at least 15 life more than your starting life total, exile Ajani, Strength of the Pride and each artifact and creature your opponents control.

Kitsune Healer

{T}: Prevent the next 1 damage that would be dealt to any target this turn.
{T}: Prevent all damage that would be dealt to target legendary creature this turn.

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.

Well of Lost Dreams

Whenever you gain life, you may pay {X}, where X is less than or equal to the amount of life you gained. If you do, draw X cards.

Crested Sunmare

Other Horses you control have indestructible.
At the beginning of each end step, if you gained life this turn, create a 5/5 white Horse creature token.