Aunt May

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

Selfless Police Captain

This creature enters with a +1/+1 counter on it.
When this creature leaves the battlefield, put its +1/+1 counters on target creature you control.

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

Amazing Alliance

Creatures you control get +1/+1.
Whenever you attack with one or more legendary creatures, you gain that much life.

Wild Pack Squad

At the beginning of combat on your turn, up to one target creature gains first strike and vigilance until end of turn.

Spider-Man, Peter Parker

Flying (This creature can't be blocked except by creatures with flying or reach.)
Whenever you gain life, put a +1/+1 counter on target creature you control. It gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Thwip!

Target creature gets +2/+2 and gains flying until end of turn. If it's a Spider, you gain 2 life.

Web Up

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

Starling, Aerial Ally

Flying
When Starling enters, another target creature you control gains flying until end of turn.

Spider-Bot

Reach
When this creature enters, you may search your library for a basic land card, reveal it, then shuffle and put that card on top.

Amateur Hero

When this creature enters, you gain 2 life.

Daily Bugle Reporters

When this creature enters, choose one —
• Puff Piece — Put a +1/+1 counter on each of up to two target creatures.
• Investigative Journalism — Return target creature card with mana value 2 or less from your graveyard to your hand.

Spectacular Tactics

Choose one —
• Put a +1/+1 counter on target creature you control. It gains hexproof until end of turn.
• Destroy target creature with power 4 or greater.

MJ, Rising Star

Vigilance (Attacking doesn't cause this creature to tap.)
Whenever you gain life, put a +1/+1 counter on MJ.