Spider Umbra

Enchant creature
Enchanted creature gets +1/+1 and has reach. (It can block creatures with flying.)
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Deathsprout

Destroy target creature. Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Lolth, Spider Queen

Whenever a creature you control dies, put a loyalty counter on Lolth, Spider Queen.
0: You draw a card and you lose 1 life.
−3: Create two 2/1 black Spider creature tokens with menace and reach.
−8: You get an emblem with "Whenever an opponent is dealt combat damage by one or more creatures you control, if that player lost less than 8 life this turn, they lose life equal to the difference."

Harmonize

Drider

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

Rakdos Signet

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.

Prevent all combat damage that would be dealt this turn.

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.)

Eaten by Spiders

Destroy target creature with flying and all Equipment attached to that creature.

Command Tower

{T}: Add one mana of any color in your commander's color identity.

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.

Swamp

Golgari Guildgate

Golgari Guildgate enters tapped.
{T}: Add {B} or {G}.

Terramorphic Expanse

{T}, Sacrifice Terramorphic Expanse: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Arachnus Spinner

Reach
Tap an untapped Spider you control: Search your graveyard and/or library for a card named Arachnus Web and put it onto the battlefield attached to target creature. If you search your library this way, shuffle.

Sentinel Spider

Sweet-Gum Recluse

Flash
Cascade
Reach
When Sweet-Gum Recluse enters, put three +1/+1 counters on each of any number of target creatures that entered this turn.

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.

Gruul Guildgate

Gruul Guildgate enters tapped.
{T}: Add {R} or {G}.

Graverobber Spider

Reach
{3}{B}: Graverobber Spider gets +X/+X until end of turn, where X is the number of creature cards in your graveyard. Activate only once each turn.

Twin-Silk Spider

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

Putrefy

Destroy target artifact or creature. It can't be regenerated.

Blightwidow

Reach (This creature can block creatures with flying.)
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Spidery Grasp

Untap target creature. It gets +2/+4 and gains reach until end of turn. (It can block creatures with flying.)

Savage Lands

Savage Lands enters tapped.
{T}: Add {B}, {R}, or {G}.

Forest

Terrifying Presence

Prevent all combat damage that would be dealt by creatures other than target creature this turn.

Penumbra Spider

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

Kodama's Reach

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Hoarding Recluse

Reach, deathtouch
When Hoarding Recluse dies, put up to one other target card from a graveyard on the bottom of its owner's library.

Golgari Signet

Gloomwidow's Feast

Destroy target creature with flying. If that creature was blue or black, create a 1/2 green Spider creature token with reach. (It can block creatures with flying.)

Mirkwood Spider

Deathtouch
Whenever Mirkwood Spider attacks, target legendary creature you control gains deathtouch until end of turn.

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Hidden Spider

When an opponent casts a creature spell with flying, if Hidden Spider is an enchantment, Hidden Spider becomes a 3/5 Spider creature with reach. (It can block creatures with flying.)

Prey Upon

Target creature you control fights target creature you don't control. (Each deals damage equal to its power to the other.)

Mountain

Kessig Recluse

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

Snarespinner

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

Stingerfling Spider

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

Murder

Cultivate

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."

Lavalanche

Lavalanche deals X damage to target player or planeswalker and each creature that player or that planeswalker's controller controls.

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.

Dragonlair Spider

Reach
Whenever an opponent casts a spell, create a 1/1 green Insect creature token.

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.

Decimate

Destroy target artifact, target creature, target enchantment, and target land. (You can't cast this spell unless you have legal choices for all its targets.)

Evolving Wilds

{T}, Sacrifice Evolving Wilds: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Brood Weaver

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

Foul Orchard

Foul Orchard enters tapped.
{T}: Add {B} or {G}.

Assault Formation

Each creature you control assigns combat damage equal to its toughness rather than its power.
{G}: Target creature with defender can attack this turn as though it didn't have defender.
{2}{G}: Creatures you control get +0/+1 until end of turn.

Thantis, the Warweaver

Vigilance, reach
All creatures attack each combat if able.
Whenever a creature attacks you or a planeswalker you control, put a +1/+1 counter on Thantis, the Warweaver.

Revenge of Ravens

Whenever a creature attacks you or a planeswalker you control, that creature's controller loses 1 life and you gain 1 life.

Webspinner Cuff

Reach
Equipped creature gets +1/+4 and has reach.
Reconfigure {4} ({4}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

Gruul Signet

Ancient Craving

You draw three cards and you lose 3 life.

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.

Skysnare Spider

Vigilance (Attacking doesn't cause this creature to tap.)
Reach (This creature can block creatures with flying.)

Arcane Signet

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.

Rugged Highlands

Rugged Highlands enters tapped.
When Rugged Highlands enters, you gain 1 life.
{T}: Add {R} or {G}.

Bloodfell Caves

Bloodfell Caves enters tapped.
When Bloodfell Caves enters, you gain 1 life.
{T}: Add {B} or {R}.

Hitchclaw Recluse

Arachnus Web

Enchant creature
Enchanted creature can't attack or block, and its activated abilities can't be activated.
At the beginning of the end step, if enchanted creature's power is 4 or greater, destroy Arachnus Web.

Witch's Web

Target creature gets +3/+3 and gains reach until end of turn. Untap it.

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.

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.

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.

Path of Ancestry

Path of Ancestry enters tapped.
{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Exotic Orchard

{T}: Add one mana of any color that a land an opponent controls could produce.

Winds of Qal Sisma

Prevent all combat damage that would be dealt this turn.
Ferocious — If you control a creature with power 4 or greater, instead prevent all combat damage that would be dealt this turn by creatures your opponents control.

Terminate

Destroy target creature. It can't be regenerated.

Deadly Recluse

Watcher in the Web

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

Overrun

Creatures you control get +3/+3 and gain trample until end of turn.

Skyfisher Spider

Reach
When Skyfisher Spider enters, you may sacrifice another creature. When you do, destroy target nonland permanent.
When Skyfisher Spider dies, you may gain 1 life for each creature card in your graveyard. If you do, exile Skyfisher Spider from your graveyard.

Sol Ring

Hatchery Spider

Reach
Undergrowth — When you cast this spell, reveal the top X cards of your library, where X is the number of creature cards in your graveyard. You may put a green permanent card with mana value X or less from among them onto the battlefield. Put the rest on the bottom of your library in a random order.

Jungle Hollow

Jungle Hollow enters tapped.
When Jungle Hollow enters, you gain 1 life.
{T}: Add {B} or {G}.