Copper Longlegs

Reach
{1}{G}, Sacrifice Copper Longlegs: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Ruins Recluse

Reach, deathtouch
{3}{G}: Put a +1/+1 counter on Ruins Recluse.

Swarmyard

{T}: Add {C}.
{T}: Regenerate target Insect, Rat, Spider, or Squirrel. (The next time it would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Ember Weaver

Reach (This creature can block creatures with flying.)
As long as you control a red permanent, Ember Weaver gets +1/+0 and has first strike.

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

Curse of Clinging Webs

Enchant player
Whenever a nontoken creature enchanted player controls dies, exile it and you create a 1/2 green Spider creature token with reach.

Stingerfling Spider

Reach
When Stingerfling Spider enters, you may destroy target creature with flying.

Drider

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

Netcaster Spider

Reach (This creature can block creatures with flying.)
Whenever Netcaster Spider blocks a creature with flying, Netcaster Spider gets +2/+0 until end of turn.

Obelisk Spider

Reach
Whenever Obelisk Spider deals combat damage to a creature, put a -1/-1 counter on that creature.
Whenever you put one or more -1/-1 counters on a creature, each opponent loses 1 life and you gain 1 life.

Hitchclaw Recluse

Shelob, Child of Ungoliant

Deathtouch, ward {2}
Other Spiders you control have deathtouch and ward {2}.
Whenever another creature dealt damage this turn by a Spider you controlled dies, create a token that's a copy of that creature, except it's a Food artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life," and it loses all other card types.

Snarespinner

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

Chainweb Aracnir

Reach
When Chainweb Aracnir enters, it deals damage equal to its power to target creature with flying an opponent controls.
Escape—{3}{G}{G}, Exile four other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)
Chainweb Aracnir escapes with three +1/+1 counters on it.

Frostweb Spider

Reach (This creature can block creatures with flying.)
Whenever Frostweb Spider blocks a creature with flying, put a +1/+1 counter on Frostweb Spider at end of combat.

Oran-Rief Recluse

Kicker {2}{G} (You may pay an additional {2}{G} as you cast this spell.)
Reach (This creature can block creatures with flying.)
When Oran-Rief Recluse enters, if it was kicked, destroy target creature with flying.

Nyx Weaver

Reach
At the beginning of your upkeep, mill two cards. (Put the top two cards of your library into your graveyard.)
{1}{B}{G}, Exile Nyx Weaver: Return target card from your graveyard to your hand.

Brood Weaver

Reach
When Brood Weaver dies, create a 1/2 green Spider creature token with reach.

Aggressive Instinct

Target creature you control deals damage equal to its power to target creature you don't control.

Grappler Spider

Reach (This creature can block creatures with flying.)

Twin-Silk Spider

Reach
When Twin-Silk Spider enters, create a 1/2 green Spider creature token with reach.

Bushwhack

Choose one —
• Search your library for a basic land card, reveal it, put it into your hand, then shuffle.
• Target creature you control fights target creature you don't control. (Each deals damage equal to its power to the other.)

Canopy Spider

Glowstone Recluse

Mutate {3}{G} (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.)
Reach
Whenever this creature mutates, put two +1/+1 counters on it.

Sporecap Spider

Rotwidow Pack

Reach
{3}{B}{G}, Exile a creature card from your graveyard: Create a 1/2 green Spider creature token with reach, then each opponent loses 1 life for each Spider you control.

Sporeweb Weaver

Reach, hexproof from blue
Whenever Sporeweb Weaver is dealt damage, you gain 1 life and create a 1/1 green Saproling creature token.

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.

Animist's Might

This spell costs {2} less to cast if it targets a legendary creature you control.
Target creature you control deals damage equal to twice its power to target creature or planeswalker you don't control.

Mountain

Penumbra Spider

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

Rib Cage Spider

Gnottvold Recluse

Ishkanah, Grafwidow

Reach
Delirium — When Ishkanah, Grafwidow enters, if there are four or more card types among cards in your graveyard, create three 1/2 green Spider creature tokens with reach.
{6}{B}: Target opponent loses 1 life for each Spider you control.

Ancient Animus

Put a +1/+1 counter on target creature you control if it's legendary. Then it fights target creature an opponent controls. (Each deals damage equal to its power to the other.)

Ambuscade

Target creature you control gets +1/+0 until end of turn. It deals damage equal to its power to target creature an opponent controls.

Bite Down

Target creature you control deals damage equal to its power to target creature or planeswalker you don't control.

Doom Weaver

Reach
Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Doom Weaver is paired with another creature, each of those creatures has "When this creature dies, draw cards equal to its power."

Deadly Recluse

Reach (This creature can block creatures with flying.)
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Gloomwidow

Reach
Gloomwidow can block only creatures with flying.

Pincer Spider

Kicker {3} (You may pay an additional {3} as you cast this spell.)
Reach (This creature can block creatures with flying.)
If Pincer Spider was kicked, it enters with a +1/+1 counter on it.

Spider Spawning

Create a 1/2 green Spider creature token with reach for each creature card in your graveyard.
Flashback {6}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)