Valley Rotcaller

Menace
Whenever Valley Rotcaller attacks, each opponent loses X life and you gain X life, where X is the number of other Squirrels, Bats, Lizards, and Rats you control.

Plains

Swamp

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.)

Essence Channeler

As long as you've lost life this turn, Essence Channeler has flying and vigilance.
Whenever you gain life, put a +1/+1 counter on Essence Channeler.
When Essence Channeler dies, put its counters on target creature you control.

Bojuka Bog

Bojuka Bog enters tapped.
When Bojuka Bog enters, exile target player's graveyard.
{T}: Add {B}.

Moonrise Cleric

Flying
Whenever Moonrise Cleric attacks, you gain 1 life.

Duskhunter Bat

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

Star Charter

Flying
At the beginning of your end step, if you gained or lost life this turn, look at the top four cards of your library. You may reveal a creature card with power 3 or less from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Diresight

Surveil 2, then draw two cards. You lose 2 life. (To surveil 2, look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Moonstone Eulogist

Flying
Whenever a creature an opponent controls dies, you create a Blood token. (It's an artifact with "{1}, {T}, Discard a card, Sacrifice this artifact: Draw a card.")
Whenever you sacrifice an artifact, put a +1/+1 counter on Moonstone Eulogist and you gain 1 life.

Moonstone Harbinger

Flying, deathtouch
Whenever you gain or lose life during your turn, Bats you control get +1/+0 and gain deathtouch until end of turn. This ability triggers only once each turn.

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.

Courier Bat

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

Batwing Brume

Prevent all combat damage that would be dealt this turn if {W} was spent to cast this spell. Each player loses 1 life for each attacking creature they control if {B} was spent to cast this spell. (Do both if {W}{B} was spent.)

Vault of the Archangel

{T}: Add {C}.
{2}{W}{B}, {T}: Creatures you control gain deathtouch and lifelink until end of turn.

Regal Bloodlord

Flying
At the beginning of each end step, if you gained life this turn, create a 1/1 black Bat creature token with flying.

Darkstar Augur

Offspring {B} (You may pay an additional {B} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
Flying
At the beginning of your upkeep, reveal the top card of your library and put that card into your hand. You lose life equal to its mana value.

Nesting Grounds

{T}: Add {C}.
{1}, {T}: Move a counter from target permanent you control onto another target permanent. Activate only as a sorcery.

Starseer Mentor

Flying, vigilance
At the beginning of your end step, if you gained or lost life this turn, target opponent loses 3 life unless they sacrifice a nonland permanent of their choice or discard a card.

Sinister Monolith

At the beginning of combat on your turn, each opponent loses 1 life and you gain 1 life.
{T}, Pay 2 life, Sacrifice Sinister Monolith: Draw two cards. Activate only as a sorcery.

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.)

Stirge

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

Tainted Field

{T}: Add {C}.
{T}: Add {W} or {B}. Activate only if you control a Swamp.

Gurmag Swiftwing

Lifecreed Duo

Flying
Whenever another creature you control enters, you gain 1 life.

Blind Hunter

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

Starscape Cleric

Offspring {2}{B} (You may pay an additional {2}{B} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
Flying
This creature can't block.
Whenever you gain life, each opponent loses 1 life.

Sonar Strike

Sonar Strike deals 4 damage to target attacking, blocking, or tapped creature. You gain 3 life if you control a Bat.

Desecrated Tomb

Whenever one or more creature cards leave your graveyard, create a 1/1 black Bat creature token with flying.

Deep-Cavern Bat

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

Wax-Wane Witness

Flying, vigilance
Whenever you gain or lose life during your turn, Wax-Wane Witness gets +1/+0 until end of turn.

Glidedive Duo

Flying
When Glidedive Duo enters, each opponent loses 2 life and you gain 2 life.

Grimclaw Bats

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

Lunar Convocation

At the beginning of your end step, if you gained life this turn, each opponent loses 1 life.
At the beginning of your end step, if you gained and lost life this turn, create a 1/1 black Bat creature token with flying.
{1}{B}, Pay 2 life: Draw a card.

Starlit Soothsayer

Flying
At the beginning of your end step, if you gained or lost life this turn, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Malakir Familiar

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

Mudflat Village

{T}: Add {C}.
{T}: Add {B}. Spend this mana only to cast a creature spell.
{1}{B}, {T}, Sacrifice Mudflat Village: Return target Bat, Lizard, Rat, or Squirrel card from your graveyard to your hand.