Foundry Screecher

Flying
This creature gets +1/+0 as long as you control an artifact.

Duskhunter Bat

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

Zoraline, Cosmos Caller

Flying, vigilance
Whenever a Bat you control attacks, you gain 1 life.
Whenever Zoraline enters or attacks, you may pay {W}{B} and 2 life. When you do, return target nonland permanent card with mana value 3 or less from your graveyard to the battlefield with a finality counter on it.

Malakir Familiar

Flying, deathtouch
Whenever you gain life, this creature 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 this creature.

Screeching Bat

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

Screeching Bat // Stalking Vampire

Dakmor Bat

Grimclaw Bats

Flying
{B}, Pay 1 life: This creature gets +1/+1 until end of turn.

Sengir Bats

Flying
Whenever a creature dealt damage by this creature this turn dies, put a +1/+1 counter on this creature.

Mirkwood Bats

Flying
Whenever you create or sacrifice a token, each opponent loses 1 life.

Dirge Bat

Mutate {4}{B}{B} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Flash
Flying
Whenever this creature mutates, destroy target creature or planeswalker an opponent controls.

Courier Bat

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

Ghastly Gloomhunter

Kicker {3}{B} (You may pay an additional {3}{B} as you cast this spell.)
Flying, lifelink
If this creature was kicked, it enters with two +1/+1 counters on it.

Deep-Cavern Bat

Flying, lifelink
When this creature enters, look at target opponent's hand. You may exile a nonland card from it until this creature leaves the battlefield.

Bloodhunter Bat

Flying
When this creature enters, target player loses 2 life and you gain 2 life.

Blind Hunter

Flying
Haunt (When this creature dies, exile it haunting target creature.)
When this creature enters or the creature it haunts dies, target player loses 2 life and you gain 2 life.

Ruin-Lurker Bat

Flying, lifelink
At the beginning of your end step, if you descended this turn, scry 1. (You descended if a permanent card was put into your graveyard from anywhere.)

Kelinore Bat

Screeching Scorchbeast

Flying, menace
Whenever this creature attacks, each player gets two rad counters.
Whenever one or more nonland cards are milled, you may create that many 2/2 black Zombie Mutant creature tokens. Do this only once each turn.

Blight Keeper

Flying
{7}{B}, {T}, Sacrifice this creature: Target opponent loses 4 life and you gain 4 life.

Stirge

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

Bartizan Bats

Flying (This creature can't be blocked except by creatures with flying or reach.)

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.)

Gloomhunter

Blighted Bat

Flying
{1}: This creature gains haste until end of turn.

Vampire Bats

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