Ajani's Pridemate

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

Plains

Healer's Flock

Light of Promise

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

Healer's Hawk

Flying
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Linden, the Steadfast Queen

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

Impassioned Orator

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

Beloved Princess

Lifelink
Beloved Princess can't be blocked by creatures with power 3 or greater.

Priest of Ancient Lore

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

Banishing Light

When this enchantment enters, exile target nonland permanent an opponent controls until this enchantment leaves the battlefield.

Fight as One

Choose one or both —
• Target Human creature you control gets +1/+1 and gains indestructible until end of turn.
• Target non-Human creature you control gets +1/+1 and gains indestructible until end of turn.

Hunted Witness

When Hunted Witness dies, create a 1/1 white Soldier creature token with lifelink.

Celestial Unicorn

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

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.