Soul's Attendant

Whenever another creature enters, you may gain 1 life.

Healer's Hawk

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

Kor Celebrant

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

White Mage's Staff

Job select (When this Equipment enters, create a 1/1 colorless Hero creature token, then attach this to it.)
Equipped creature gets +1/+1, has "Whenever this creature attacks, you gain 1 life," and is a Cleric in addition to its other types.
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Plains

Dazzling Angel

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

You're Not Alone

Target creature gets +2/+2 until end of turn. If you control three or more creatures, it gets +4/+4 until end of turn instead.

Disenchant

Caduceus, Staff of Hermes

Equipped creature has lifelink.
As long as you have 30 or more life, equipped creature gets +5/+5 and has indestructible and "Prevent all damage that would be dealt to this creature."
Equip {W}{W}

Banishing Light

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

Angelic Gift

Enchant creature
When this Aura enters, draw a card.
Enchanted creature has flying.