Dementia Bat

Flying
{4}{B}, Sacrifice Dementia Bat: Target player discards two cards.

Gurmag Swiftwing

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.

Kelinore Bat

Ghastly Gloomhunter

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

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

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

Stirge

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

Foundry Screecher

Flying
Foundry Screecher gets +1/+0 as long as you control an artifact.

Eyetwitch

Flying
When Eyetwitch dies, learn. (You may reveal a Lesson card you own from outside the game and put it into your hand, or discard a card to draw a card.)

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.

Mirkwood Bats

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

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

Malakir Familiar

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

Deep-Cavern Bat

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

Bloodhunter Bat

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

Sengir Bats

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

Blighted Bat

Flying
{1}: Blighted Bat gains haste until end of turn.

Blight Keeper

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

Bartizan Bats

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

Grimclaw Bats

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

Temple of the Dead

(Transforms from Aclazotz, Deepest Betrayal.)
{T}: Add {B}.
{2}{B}, {T}: Transform Temple of the Dead. Activate only if a player has one or fewer cards in hand and only as a sorcery.

Aclazotz, Deepest Betrayal

Flying, lifelink
Whenever Aclazotz attacks, each opponent discards a card. For each opponent who can't, you draw a card.
Whenever an opponent discards a land card, create a 1/1 black Bat creature token with flying.
When Aclazotz dies, return it to the battlefield tapped and transformed under its owner's control.

Aclazotz, Deepest Betrayal // Temple of the Dead

Marrow Bats

Flying
Pay 4 life: Regenerate Marrow Bats.

Dakmor Bat

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.