Sunbond

Enchant creature
Enchanted creature has "Whenever you gain life, put that many +1/+1 counters on this creature."

Courser of Kruphix

Play with the top card of your library revealed.
You may play lands from the top of your library.
Landfall — Whenever a land you control enters, you gain 1 life.

Forest

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.

Plains

Heroes' Reunion

Ageless Entity

Whenever you gain life, put that many +1/+1 counters on Ageless Entity.

Wall of Reverence

Defender, flying
At the beginning of your end step, you may gain life equal to the power of target creature you control.

Sheltering Word

Target creature you control gains hexproof until end of turn. You gain life equal to that creature's toughness. (A creature with hexproof can't be the target of spells or abilities your opponents control.)

Voracious Wurm

Voracious Wurm enters with X +1/+1 counters on it, where X is the amount of life you've gained this turn.