Inspiring Overseer

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

Soul Warden

Whenever another creature enters, you gain 1 life.

Tamiyo's Safekeeping

Target permanent you control gains hexproof and indestructible until end of turn. You gain 2 life. (A permanent with hexproof and indestructible can't be the target of spells or abilities your opponents control. Damage and effects that say "destroy" don't destroy it.)

Trelasarra, Moon Dancer

Whenever you gain life, put a +1/+1 counter on Trelasarra, Moon Dancer and scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Soul's Attendant

Whenever another creature enters, you may gain 1 life.

Answered Prayers

Whenever a creature you control enters, you gain 1 life. If Answered Prayers isn't a creature, it becomes a 3/3 Angel creature with flying in addition to its other types until end of turn.

Vigorous Charge

Kicker {W} (You may pay an additional {W} as you cast this spell.)
Target creature gains trample until end of turn. Whenever that creature deals combat damage this turn, if this spell was kicked, you gain life equal to that damage.

Jaddi Offshoot

Defender
Landfall — Whenever a land you control enters, you gain 1 life.

Wax-Wane Witness

Flying, vigilance
Whenever you gain or lose life during your turn, Wax-Wane Witness gets +1/+0 until end of turn.

Shield of the Oversoul

Enchant creature
As long as enchanted creature is green, it gets +1/+1 and has indestructible. (Damage and effects that say "destroy" don't destroy it. If its toughness is 0 or less, it's still put into its owner's graveyard.)
As long as enchanted creature is white, it gets +1/+1 and has flying.

Avacyn's Pilgrim

Essence Warden

Grazing Gladehart

Landfall — Whenever a land you control enters, you may gain 2 life.

Lifecreed Duo

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

Kazandu Nectarpot

Landfall — Whenever a land you control enters, you gain 1 life.

Verdant Haven

Enchant land
When Verdant Haven enters, you gain 2 life.
Whenever enchanted land is tapped for mana, its controller adds an additional one mana of any color.

Sylvan Shepherd

Vigilance
Whenever Sylvan Shepherd attacks, roll a d20.
1—9 | You gain 1 life.
10—19 | You gain 2 life.
20 | You gain 5 life.

Luminous Phantom

Flying
Whenever another creature you control leaves the battlefield, you gain 1 life.
If Luminous Phantom would be put into a graveyard from anywhere, exile it instead.

Lunarch Veteran

Whenever another creature you control enters, you gain 1 life.
Disturb {1}{W} (You may cast this card from your graveyard transformed for its disturb cost.)

Lunarch Veteran // Luminous Phantom

Armadillo Cloak

Enchant creature
Enchanted creature gets +2/+2 and has trample.
Whenever enchanted creature deals damage, you gain that much life.

Celestial Unicorn

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

Kor Celebrant

Whenever Kor Celebrant or another creature you control enters, you gain 1 life.

Social Climber

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

Holy Cow

Flash
Flying
When Holy Cow enters, you gain 2 life and scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Spirit Link

Enchant creature (Target a creature as you cast this. This card enters attached to that creature.)
Whenever enchanted creature deals damage, you gain that much life.

Ajani's Mantra

At the beginning of your upkeep, you may gain 1 life.

Impassioned Orator

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

Suture Priest

Whenever another creature you control enters, you may gain 1 life.
Whenever a creature an opponent controls enters, you may have that player lose 1 life.