Celestial Unicorn

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

The Book of Exalted Deeds

At the beginning of your end step, if you gained 3 or more life this turn, create a 3/3 white Angel creature token with flying.
{W}{W}{W}, {T}, Exile The Book of Exalted Deeds: Put an enlightened counter on target Angel. It gains "You can't lose the game and your opponents can't win the game." Activate only as a sorcery.

Ajani's Pridemate

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

Speaker of the Heavens

Vigilance, lifelink (Attacking doesn't cause this creature to tap. Damage dealt by this creature also causes you to gain that much life.)
{T}: Create a 4/4 white Angel creature token with flying. Activate only if you have at least 7 life more than your starting life total and only as a sorcery.

Healer's Hawk

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

It That Rides as One

Lone Rider

First strike, lifelink
At the beginning of the end step, if you gained 3 or more life this turn, transform Lone Rider.

Lone Rider // It That Rides as One

Alseid of Life's Bounty

Lifelink
{1}, Sacrifice Alseid of Life's Bounty: Target creature or enchantment you control gains protection from the color of your choice until end of turn.