Getting

Fumigate

Destroy all creatures. You gain 1 life for each creature destroyed this way.

Healer's Hawk

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

Cat Collector

When this creature enters, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
Whenever you gain life for the first time during each of your turns, create a 1/1 white Cat creature token.

Linden, the Steadfast Queen

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

Diamond Mare

As Diamond Mare enters, choose a color.
Whenever you cast a spell of the chosen color, you gain 1 life.

Have

Plains

Stroke of Midnight

Destroy target nonland permanent. Its controller creates a 1/1 white Human creature token.

Make a Stand

Creatures you control get +1/+0 and gain indestructible until end of turn. (Damage and effects that say "destroy" don't destroy them.)

Inspiring Overseer

Flying
When this creature enters, you gain 1 life and draw a card.

Ajani's Pridemate

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

Angel of Vitality

Flying
If you would gain life, you gain that much life plus 1 instead.
This creature gets +2/+2 as long as you have 25 or more life.

Hinterland Sanctifier

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