Fumulus, the Infestation

Flying, deathtouch
Whenever a player sacrifices a nontoken creature, create a 1/1 black Insect creature token with flying.
Whenever an Insect, Leech, Slug, or Worm you control attacks, defending player loses 1 life and you gain 1 life.

Caustic Caterpillar

{1}{G}, Sacrifice this creature: Destroy target artifact or enchantment.

Canoptek Tomb Sentinel

Vigilance
Exile Cannon — When this creature enters from a graveyard, exile up to one target nonland permanent.
Unearth {7} ({7}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Aatchik, Emerald Radian

When Aatchik enters, create a 1/1 green Insect creature token for each artifact and/or creature card in your graveyard.
Whenever another Insect you control dies, put a +1/+1 counter on Aatchik. Each opponent loses 1 life.

Nameless Inversion

Changeling (This card is every creature type.)
Target creature gets +3/-3 and loses all creature types until end of turn.

Zask, Skittering Swarmlord

You may play lands and cast Insect spells from your graveyard.
Whenever another Insect you control dies, put it on the bottom of its owner's library, then mill two cards. (Put the top two cards of your library into your graveyard.)
{1}{B/G}: Target Insect gets +1/+0 and gains deathtouch until end of turn. ({B/G} can be paid with either {B} or {G}.)

Chitin Gravestalker

This spell costs {1} less to cast for each artifact and/or creature card in your graveyard.
Cycling {2} ({2}, Discard this card: Draw a card.)

Springheart Nantuko

Bestow {1}{G}
Enchanted creature gets +1/+1.
Landfall — Whenever a land you control enters, you may pay {1}{G} if this permanent is attached to a creature you control. If you do, create a token that's a copy of that creature. If you didn't create a token this way, create a 1/1 green Insect creature token.

Skittering Cicada

Flash
You may cast colorless spells as though they had flash.
Whenever you cast a colorless spell, until end of turn, this creature gains trample and gets +X/+X, where X is that spell's mana value.

Formless Genesis

Changeling (This card is every creature type.)
Create an X/X colorless Shapeshifter creature token with changeling and deathtouch, where X is the number of land cards in your graveyard.
Retrace (You may cast this card from your graveyard by discarding a land card in addition to paying its other costs.)

Realmwalker

Changeling (This card is every creature type.)
As this creature enters, choose a creature type.
You may look at the top card of your library any time.
You may cast creature spells of the chosen type from the top of your library.

Hex Parasite

{X}{B/P}: Remove up to X counters from target permanent. For each counter removed this way, this creature gets +1/+0 until end of turn. ({B/P} can be paid with either {B} or 2 life.)

Webstrike Elite

Reach
Cycling {X}{G}{G} ({X}{G}{G}, Discard this card: Draw a card.)
When you cycle this card, destroy up to one target artifact or enchantment with mana value X.

Grist, the Plague Swarm

+1: Create a 1/1 black and green Insect creature token, then mill two cards. Put a deathtouch counter on the token if a black card was milled this way.
−2: Destroy target artifact or enchantment.
−6: For each creature card in your graveyard, create a token that's a copy of it, except it's a 1/1 black and green Insect.

Grist, Voracious Larva

Deathtouch
Whenever Grist or another creature you control enters, if it entered from your graveyard or you cast it from your graveyard, you may pay {G}. If you do, exile Grist, then return it to the battlefield transformed under its owner's control.

Grist, Voracious Larva // Grist, the Plague Swarm

Kraul Harpooner

Reach
Undergrowth — When this creature enters, choose up to one target creature you don't control with flying. This creature gets +X/+0 until end of turn, where X is the number of creature cards in your graveyard, then you may have this creature fight that creature.

Amzu, Swarm's Hunger

Flying, menace
Other Insects you control have menace.
Whenever one or more cards leave your graveyard, you may create a 1/1 black and green Insect creature token, then put a number of +1/+1 counters on it equal to the greatest mana value among those cards. Do this only once each turn.

Ant Queen

{1}{G}: Create a 1/1 green Insect creature token.

Carrion Grub

This creature gets +X/+0, where X is the greatest power among creature cards in your graveyard.
When this creature enters, mill four cards. (Put the top four cards of your library into your graveyard.)

Scouring Swarm

Flying
Whenever you sacrifice a land, create a tapped token that's a copy of this creature if seven or more land cards are in your graveyard. Otherwise, create a tapped 1/1 black Insect creature token with flying.

Molt Tender

{T}: Mill a card. (Put the top card of your library into your graveyard.)
{T}, Exile a card from your graveyard: Add one mana of any color.

Seedship Broodtender

When this creature enters, mill three cards. (Put the top three cards of your library into your graveyard.)
{3}{B}{G}, Sacrifice this creature: Return target creature or Spacecraft card from your graveyard to the battlefield. Activate only as a sorcery.

Hornet Queen

Flying, deathtouch
When this creature enters, create four 1/1 green Insect creature tokens with flying and deathtouch.

Grist, the Hunger Tide

As long as Grist isn't on the battlefield, it's a 1/1 Insect creature in addition to its other types.
+1: Create a 1/1 black and green Insect creature token, then mill a card. If an Insect card was milled this way, put a loyalty counter on Grist and repeat this process.
−2: You may sacrifice a creature. When you do, destroy target creature or planeswalker.
−5: Each opponent loses life equal to the number of creature cards in your graveyard.

Dross Hopper

Sacrifice a creature: This creature gains flying until end of turn.

Swarm Culler

Flying
Whenever this creature becomes tapped, you may sacrifice another creature or artifact. If you do, draw a card.

Spring-Leaf Avenger

Ninjutsu {3}{G} ({3}{G}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever this creature deals combat damage to a player, return target permanent card from your graveyard to your hand.

Altanak, the Thrice-Called

Trample
Whenever Altanak becomes the target of a spell or ability an opponent controls, draw a card.
{1}{G}, Discard this card: Return target land card from your graveyard to the battlefield tapped.

Changeling Wayfinder

Changeling (This card is every creature type.)
When this creature enters, you may search your library for a basic land card, reveal it, put it into your hand, then shuffle.

Lord Dregg, Insect Invader

Flying
Disappear — At the beginning of your end step, if a permanent left the battlefield under your control this turn, create a 1/1 black Insect Warrior creature token with flying.
{3}{G}, Sacrifice a token: Draw a card.

Kazandu Nectarpot

Landfall — Whenever a land you control enters, you gain 1 life.

Eumidian Terrabotanist

Horizon Explorer

Lands you control enter untapped.
Whenever you attack a player, create a Lander token. (It's an artifact with "{2}, {T}, Sacrifice this token: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.")

Gleancrawler

({B/G} can be paid with either {B} or {G}.)
Trample
At the beginning of your end step, return to your hand all creature cards in your graveyard that were put there from the battlefield this turn.

Haywire Mite

When this creature dies, you gain 2 life.
{G}, Sacrifice this creature: Exile target noncreature artifact or noncreature enchantment.

Mazirek, Kraul Death Priest

Flying
Whenever a player sacrifices another permanent, put a +1/+1 counter on each creature you control.

Scute Swarm

Landfall — Whenever a land you control enters, create a 1/1 green Insect creature token. If you control six or more lands, create a token that's a copy of this creature instead.

Nantuko Husk

Sacrifice a creature: This creature gets +2/+2 until end of turn.

Graveshifter

Changeling (This card is every creature type.)
When this creature enters, you may return target creature card from your graveyard to your hand.

Mutable Explorer

Changeling (This card is every creature type.)
When this creature enters, create a tapped Mutavault token. (It's a land with "{T}: Add {C}" and "{1}: This token becomes a 2/2 creature with all creature types until end of turn. It's still a land.")

Masked Vandal

Changeling (This card is every creature type.)
When this creature enters, you may exile a creature card from your graveyard. If you do, exile target artifact or enchantment an opponent controls.

Chomping Changeling

Changeling (This card is every creature type.)
When this creature enters, destroy up to one target artifact or enchantment.

Gene Pollinator

{T}, Tap an untapped permanent you control: Add one mana of any color.

Seedship Agrarian

Whenever this creature becomes tapped, create a Lander token. (It's an artifact with "{2}, {T}, Sacrifice this token: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.")
Landfall — Whenever a land you control enters, put a +1/+1 counter on this creature.