Malakir Familiar

Flying, deathtouch
Whenever you gain life, Malakir Familiar gets +1/+1 until end of turn.

Stalking Vampire

At the beginning of your upkeep, you may pay {2}{B}{B}. If you do, transform Stalking Vampire.

Screeching Bat

Flying
At the beginning of your upkeep, you may pay {2}{B}{B}. If you do, transform Screeching Bat.

Screeching Bat // Stalking Vampire

Vampire Bats

Flying (This creature can't be blocked except by creatures with flying or reach.)
{B}: Vampire Bats gets +1/+0 until end of turn. Activate no more than twice each turn.

Bloodhunter Bat

Flying
When Bloodhunter Bat enters the battlefield, target player loses 2 life and you gain 2 life.

Gurmag Swiftwing

Duskhunter Bat

Bloodthirst 1 (If an opponent was dealt damage this turn, this creature enters the battlefield with a +1/+1 counter on it.)
Flying

Skyblinder Staff

Equipped creature gets +1/+0 and can't be blocked by creatures with flying.
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Courier Bat

Flying
When Courier Bat enters the battlefield, if you gained life this turn, return up to one target creature card from your graveyard to your hand.

Stirge

Flying
Stirge can't block.
Blood Drain — {1}{B}, Pay 1 life, Sacrifice Stirge: Draw a card.

Henrika, Infernal Seer

Flying, deathtouch, lifelink
{1}{B}{B}: Each creature you control with flying, deathtouch, and/or lifelink gets +1/+0 until end of turn.

Henrika Domnathi

Flying
At the beginning of combat on your turn, choose one that hasn't been chosen —
• Each player sacrifices a creature.
• You draw a card and you lose 1 life.
• Transform Henrika Domnathi.

Henrika Domnathi // Henrika, Infernal Seer

Swamp

Basilica Screecher

Flying
Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)