Drana's Emissary

Flying
At the beginning of your upkeep, each opponent loses 1 life and you gain 1 life.

Stinging Study

You draw X cards and you lose X life, where X is the mana value of a commander you own on the battlefield or in the command zone.

Vampire Nighthawk

Flying
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Verrak, Warped Sengir

Flying, deathtouch, lifelink
Whenever you activate an ability that isn't a mana ability, if life was paid to activate it, you may pay that much life again. If you do, copy that ability. You may choose new targets for the copy.

Sanguine Bond

Whenever you gain life, target opponent loses that much life.

Licia, Sanguine Tribune

This spell costs {1} less to cast for each 1 life you gained this turn.
First strike, lifelink
Pay 5 life: Put three +1/+1 counters on Licia. Activate only during your turn and only once each turn.

Phyrexian Arena

At the beginning of your upkeep, you draw a card and you lose 1 life.

Creeping Bloodsucker

At the beginning of your upkeep, this creature deals 1 damage to each opponent. You gain life equal to the damage dealt this way.

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.

Font of Agonies

Whenever you pay life, put that many blood counters on this enchantment.
{1}{B}, Remove four blood counters from this enchantment: Destroy target creature.

Markov Purifier

Lifelink
At the beginning of your end step, if you gained life this turn, you may pay {2}. If you do, draw a card.

Well of Lost Dreams

Whenever you gain life, you may pay {X}, where X is less than or equal to the amount of life you gained. If you do, draw X cards.

Chandra's Ignition

Target creature you control deals damage equal to its power to each other creature and each opponent.

Elenda, Saint of Dusk

Lifelink, hexproof from instants
As long as your life total is greater than your starting life total, Elenda gets +1/+1 and has menace. Elenda gets an additional +5/+5 as long as your life total is at least 10 greater than your starting life total.