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.

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.)

Winding Way

Choose creature or land. Reveal the top four cards of your library. Put all cards of the chosen type revealed this way into your hand and the rest into your graveyard.

Forest

Watcher in the Web

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

Swamp

Ruins Recluse

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

Bojuka Bog

This land enters tapped.
When this land enters, exile target player's graveyard.
{T}: Add {B}.

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.)

Gnaw to the Bone

You gain 2 life for each creature card in your graveyard.
Flashback {2}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Haywire Mite

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

Vigor Mortis

Return target creature card from your graveyard to the battlefield. If {G} was spent to cast this spell, that creature enters with an additional +1/+1 counter on it.

Jungle Hollow

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {B} or {G}.

Twin-Silk Spider

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

Ishkanah, Grafwidow

Reach
Delirium — When Ishkanah 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.

Putrefy

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

Hissing Quagmire

This land enters tapped.
{T}: Add {B} or {G}.
{1}{B}{G}: This land becomes a 2/2 black and green Elemental creature with deathtouch until end of turn. It's still a land.

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.)

Penumbra Spider

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

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 token: You gain 3 life," and it loses all other card types.

Hooded Blightfang

Deathtouch
Whenever a creature you control with deathtouch attacks, each opponent loses 1 life and you gain 1 life.
Whenever a creature you control with deathtouch deals damage to a planeswalker, destroy that planeswalker.

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.

Arachnogenesis

Create X 1/2 green Spider creature tokens with reach, where X is the number of creatures attacking you. Prevent all combat damage that would be dealt this turn by non-Spider creatures.