Green Goblin, Revenant

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

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.)

Asmoranomardicadaistinaculdacar

As long as you've discarded a card this turn, you may pay {B/R} to cast this spell.
When Asmoranomardicadaistinaculdacar enters, you may search your library for a card named The Underworld Cookbook, reveal it, put it into your hand, then shuffle.
Sacrifice two Foods: Target creature deals 6 damage to itself.

Ultimate Green Goblin

At the beginning of your upkeep, discard a card, then create a Treasure token.
Mayhem {2}{B/R} (You may cast this card from your graveyard for {2}{B/R} if you discarded it this turn. Timing rules still apply.)

Anje Falkenrath

Haste
{T}, Discard a card: Draw a card.
Whenever you discard a card, if it has madness, untap Anje Falkenrath.

Green Goblin, Nemesis

Flying
Whenever you discard a nonland card, put a +1/+1 counter on target Goblin you control.
Whenever you discard a land card, create a tapped Treasure token.

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}