Discord, Lord of Disharmony

Flying
At the beginning of your end step, choose a random nonland Magic card name. Until your next end step, you may cast a copy of a spell with that name, and mana of any type can be spent to cast it. If you cast a spell this way, copy this ability if Discord is on the battlefield.

Urabrask the Hidden

Creatures you control have haste.
Creatures your opponents control enter the battlefield tapped.

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

Chaos Warp

The owner of target permanent shuffles it into their library, then reveals the top card of their library. If it's a permanent card, they put it onto the battlefield.

Lagomos, Hand of Hatred

At the beginning of combat on your turn, create a 2/1 red Elemental creature token with trample and haste. Sacrifice it at the beginning of the next end step.
{T}: Search your library for a card, put it into your hand, then shuffle. Activate only if five or more creatures died this turn.

Raucous Theater

({T}: Add {B} or {R}.)
Raucous Theater enters the battlefield tapped.
When Raucous Theater enters the battlefield, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)