Aetherflux Reservoir

Whenever you cast a spell, you gain 1 life for each spell you've cast this turn.
Pay 50 life: Aetherflux Reservoir deals 50 damage to any target.

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.

Heron of Hope

Flying
If you would gain life, you gain that much life plus 1 instead.
{1}{W}: Heron of Hope gains lifelink until end of turn.

Ancestor Dragon

Flying
Whenever one or more creatures you control attack, you gain 1 life for each attacking creature.

Riot Control

You gain 1 life for each creature your opponents control. Prevent all damage that would be dealt to you this turn.

Alhammarret's Archive

If you would gain life, you gain twice that much life instead.
If you would draw a card except the first one you draw in each of your draw steps, draw two cards instead.

Orim's Prayer

Whenever one or more creatures attack you, you gain 1 life for each attacking creature.

Gerrard Capashen

At the beginning of your upkeep, you gain 1 life for each card in target opponent's hand.
{3}{W}: Tap target creature. Activate only if Gerrard Capashen is attacking.

Fumigate

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

Atalya, Samite Master

{X}, {T}: Choose one —
• Prevent the next X damage that would be dealt to target creature this turn. Spend only white mana on X.
• You gain X life. Spend only white mana on X.

Boon Reflection

If you would gain life, you gain twice that much life instead.

Knight of Dawn's Light

First strike
If you would gain life, you gain that much life plus 1 instead.
{1}{W}: Knight of Dawn's Light gets +1/+1 until end of turn.

Elspeth Tirel

+2: You gain 1 life for each creature you control.
−2: Create three 1/1 white Soldier creature tokens.
−5: Destroy all other permanents except for lands and tokens.

Rhox Faithmender

Lifelink (Damage dealt by this creature also causes you to gain that much life.)
If you would gain life, you gain twice that much life instead.

Cleric Class

(Gain the next level as a sorcery to add its ability.)
If you would gain life, you gain that much life plus 1 instead.
{3}{W}: Level 2
Whenever you gain life, put a +1/+1 counter on target creature you control.
{4}{W}: Level 3
When this Class becomes level 3, return target creature card from your graveyard to the battlefield. You gain life equal to that creature's toughness.