Xantid Swarm

Flying
Whenever Xantid Swarm attacks, defending player can't cast spells this turn.

Hagra Constrictor

Hagra Constrictor enters with two +1/+1 counters on it.
Each creature you control with a +1/+1 counter on it has menace. (A creature with menace can't be blocked except by two or more creatures.)

Voracious Typhon

Escape—{5}{G}{G}, Exile four other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)
Voracious Typhon escapes with three +1/+1 counters on it.

Blight Keeper

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

Malakir Familiar

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

Pharika's Chosen

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Killer Bees

Flying
{G}: Killer Bees gets +1/+1 until end of turn.

Yuan-Ti Fang-Blade

Deathtouch
Whenever Yuan-Ti Fang-Blade deals combat damage to a player, venture into the dungeon. (Enter the first room or advance to the next room.)

Arasta of the Endless Web

Reach
Whenever an opponent casts an instant or sorcery spell, create a 1/2 green Spider creature token with reach.

Giant Adephage

Trample
Whenever Giant Adephage deals combat damage to a player, create a token that's a copy of Giant Adephage.

Watcher in the Web

Reach (This creature can block creatures with flying.)
Watcher in the Web can block an additional seven creatures each combat.

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.

Snarespinner

Reach
Whenever Snarespinner blocks a creature with flying, Snarespinner gets +2/+0 until end of turn.

Drider

Reach
Whenever Drider deals combat damage to a player, create a 2/1 black Spider creature token with menace and reach.

Snake of the Golden Grove

Tribute 3 (As this creature enters, an opponent of your choice may put three +1/+1 counters on it.)
When Snake of the Golden Grove enters, if tribute wasn't paid, you gain 4 life.

Gurmag Swiftwing

Moss Viper

Stirge

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

Signal Pest

Battle cry (Whenever this creature attacks, each other attacking creature gets +1/+0 until end of turn.)
Signal Pest can't be blocked except by creatures with flying or reach.

Search for Blex

Look at the top five cards of your library. You may put any number of them into your hand and the rest into your graveyard. You lose 3 life for each card you put into your hand this way.

Blex, Vexing Pest

Other Pests, Bats, Insects, Snakes, and Spiders you control get +1/+1.
When Blex, Vexing Pest dies, you gain 4 life.

Blex, Vexing Pest // Search for Blex

Mold Adder

Whenever an opponent casts a blue or black spell, you may put a +1/+1 counter on this creature.

Penumbra Spider

Reach
When Penumbra Spider dies, create a 2/4 black Spider creature token with reach.

Nessian Hornbeetle

At the beginning of combat on your turn, if you control another creature with power 4 or greater, put a +1/+1 counter on this creature.