Web-Warriors

When this creature enters, put a +1/+1 counter on each other creature you control.

Supportive Parents

Tap two untapped creatures you control: Add one mana of any color.

Bagel and Schmear

Share — {W}, {T}, Sacrifice this artifact: Put a +1/+1 counter on up to one target creature. Draw a card. Activate only as a sorcery.
Nosh — {2}, {T}, Sacrifice this artifact: You gain 3 life and draw a card.

Gallant Citizen

Sun-Spider, Nimble Webber

During your turn, Sun-Spider has flying.
When Sun-Spider enters, search your library for an Aura or Equipment card, reveal it, put it into your hand, then shuffle.

Spider-Man No More

Enchant creature
Enchanted creature is a Citizen with base power and toughness 1/1. It has defender and loses all other abilities. (It also loses all other creature types.)

Web Up

When this enchantment enters, exile target nonland permanent an opponent controls until this enchantment leaves the battlefield.

Spider-Man, Web-Slinger

Web-slinging {W} (You may cast this spell for {W} if you also return a tapped creature you control to its owner's hand.)

Plains

Sudden Strike

Destroy target attacking or blocking creature.

Spider-Girl, Legacy Hero

During your turn, Spider-Girl has flying.
When Spider-Girl leaves the battlefield, create a 1/1 green and white Human Citizen creature token.

Forest

Aunt May

Whenever another creature you control enters, you gain 1 life. If it's a Spider, put a +1/+1 counter on it.

Vibrant Cityscape

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

Kapow!

Put a +1/+1 counter on target creature you control. It fights target creature an opponent controls. (Each deals damage equal to its power to the other.)

Arachne, Psionic Weaver

Web-slinging {W} (You may cast this spell for {W} if you also return a tapped creature you control to its owner's hand.)
As Arachne enters, look at an opponent's hand, then choose a card type other than creature.
Spells of the chosen type cost {1} more to cast.

Flash Thompson, Spider-Fan

Flash
When Flash Thompson enters, choose one or both —
• Heckle — Tap target creature.
• Hero Worship — Untap target creature.

Wall Crawl

When this enchantment enters, create a 2/1 green Spider creature token with reach, then you gain 1 life for each Spider you control.
Spiders you control get +1/+1 and can't be blocked by creatures with defender.

Spider-Man, Brooklyn Visionary

Web-slinging {2}{G} (You may cast this spell for {2}{G} if you also return a tapped creature you control to its owner's hand.)
When Spider-Man enters, search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Suburban Sanctuary

This land enters tapped.
{T}: Add {G} or {W}.
{4}, {T}: Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Spiders-Man, Heroic Horde

Web-slinging {4}{G}{G} (You may cast this spell for {4}{G}{G} if you also return a tapped creature you control to its owner's hand.)
When Spiders-Man enters, if they were cast using web-slinging, you gain 3 life and create two 2/1 green Spider creature tokens with reach.

Spider-UK

Web-slinging {2}{W} (You may cast this spell for {2}{W} if you also return a tapped creature you control to its owner's hand.)
At the beginning of your end step, if two or more creatures entered the battlefield under your control this turn, you draw a card and gain 2 life.

Island

Guy in the Chair

{T}: Add one mana of any color.
Web Support — {2}{G}, {T}: Put a +1/+1 counter on target Spider. Activate only as a sorcery.

Urban Retreat

This land enters tapped.
{T}: Add {G}, {W}, or {U}.
{2}, Return a tapped creature you control to its owner's hand: Put this card from your hand onto the battlefield. Activate only as a sorcery.

Spider-Rex, Daring Dino

Reach, trample
Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)

Skyward Spider

Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
This creature has flying as long as it's modified. (Equipment, Auras you control, and counters are modifications.)

Origin of Spider-Man

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Create a 2/1 green Spider creature token with reach.
II — Put a +1/+1 counter on target creature you control. It becomes a legendary Spider Hero in addition to its other types.
III — Target creature you control gains double strike until end of turn.

City Pigeon

Flying
When this creature leaves the battlefield, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")