Parker Luck

At the beginning of your end step, two target players each reveal the top card of their library. They each lose life equal to the mana value of the card revealed by the other player. Then they each put the card they revealed into their hand.

Green Goblin, Revenant

Flying, deathtouch
Whenever Green Goblin attacks, discard a card. Then draw a card for each card you've discarded this turn.

Swamp

Scorpion's Sting

Target creature gets -3/-3 until end of turn.

Raging Goblinoids

Haste
Mayhem {2}{R} (You may cast this card from your graveyard for {2}{R} if you discarded it this turn. Timing rules still apply.)

Electro's Bolt

Electro's Bolt deals 4 damage to target creature.
Mayhem {1}{R} (You may cast this card from your graveyard for {1}{R} if you discarded it this turn. Timing rules still apply.)

Spider-Islanders

Mayhem {1}{R} (You may cast this card from your graveyard for {1}{R} if you discarded it this turn. Timing rules still apply.)

Multiversal Passage

As this land enters, choose a basic land type. Then you may pay 2 life. If you don't, it enters tapped.
This land is the chosen type.

Hobgoblin, Mantled Marauder

Flying, haste
Whenever you discard a card, Hobgoblin gets +2/+0 until end of turn.

Venom, Evil Unleashed

Deathtouch
{2}{B}, Exile this card from your graveyard: Put two +1/+1 counters on target creature. It gains deathtouch until end of turn. Activate only as a sorcery.

Stegron the Dinosaur Man

Menace (This creature can't be blocked except by two or more creatures.)
Dinosaur Formula — {1}{R}, Discard this card: Until end of turn, target creature you control gets +3/+1 and becomes a Dinosaur in addition to its other types.

Scarlet Spider, Kaine

Menace (This creature can't be blocked except by two or more creatures.)
When Scarlet Spider enters, you may discard a card. If you do, put a +1/+1 counter on him.
Mayhem {B/R} (You may cast this card from your graveyard for {B/R} if you discarded it this turn. Timing rules still apply.)

Vibrant Cityscape

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

Swarm, Being of Bees

Flash
Flying
Mayhem {B} (You may cast this card from your graveyard for {B} if you discarded it this turn. Timing rules still apply.)

Ominous Asylum

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

Romantic Rendezvous

Masked Meower

Haste
Discard a card, Sacrifice this creature: Draw a card.

Pumpkin Bombardment

As an additional cost to cast this spell, discard a card or pay {2}.
Pumpkin Bombardment deals 3 damage to target creature.

Mechanical Mobster

When this creature enters, exile up to one target card from a graveyard. Target creature you control connives. (Draw a card, then discard a card. If you discarded a nonland card, put a +1/+1 counter on that creature.)

Carnage, Crimson Chaos

Trample
When Carnage enters, return target creature card with mana value 3 or less from your graveyard to the battlefield. It gains "This creature attacks each combat if able" and "When this creature deals combat damage to a player, sacrifice it."
Mayhem {B}{R}

Alien Symbiosis

Enchant creature
Enchanted creature gets +1/+1, has menace, and is a Symbiote in addition to its other types.
You may cast this card from your graveyard by discarding a card in addition to paying its other costs.

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.

Mountain

Rocket-Powered Goblin Glider

When this Equipment enters, if it was cast from your graveyard, attach it to target creature you control.
Equipped creature gets +2/+0 and has flying and haste.
Equip {2}
Mayhem {2}

Villainous Wrath

Target opponent loses life equal to the number of creatures they control. Then destroy all creatures.

Inner Demons Gangsters

Discard a card: This creature gets +1/+0 and gains menace until end of turn. Activate only as a sorcery. (It can't be blocked except by two or more creatures.)

Shadow of the Goblin

Unreliable Visions — At the beginning of your first main phase, discard a card. If you do, draw a card.
Undying Vengeance — Whenever you play a land or cast a spell from anywhere other than your hand, this enchantment deals 1 damage to each opponent.

Shriek, Treblemaker

At the beginning of your first main phase, you may discard a card. When you do, target creature can't block this turn.
Sonic Blast — Whenever a creature an opponent controls dies, Shriek deals 1 damage to that player.