Costume Closet

This artifact enters with two +1/+1 counters on it.
{T}: Move a +1/+1 counter from this artifact onto target creature you control. Activate only as a sorcery.
Whenever a modified creature you control leaves the battlefield, put a +1/+1 counter on this artifact. (Equipment, Auras you control, and counters are modifications.)

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.

Flash Thompson, Spider-Fan

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

Ultimate Spider-Man

First strike, haste
Camouflage — {2}: Put a +1/+1 counter on Ultimate Spider-Man. He gains hexproof and becomes colorless until end of turn.
Whenever you attack, double the number of each kind of counter on each Spider and legendary creature you control.

Miles Morales

When Miles Morales enters, put a +1/+1 counter on each of up to two target creatures.
{3}{R}{G}{W}: Transform Miles Morales. Activate only as a sorcery.

Miles Morales // Ultimate Spider-Man

Aunt May

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