Humility

All creatures lose all abilities and have base power and toughness 1/1.

Impending Disaster

At the beginning of your upkeep, if there are seven or more lands on the battlefield, sacrifice Impending Disaster and destroy all lands.

Rule of Law

Each player can't cast more than one spell each turn.

Blood Moon

Child of Alara

Trample
When Child of Alara dies, destroy all nonland permanents. They can't be regenerated.

Armageddon

Sunder

Plains

Epicenter

Target player sacrifices a land.
Threshold — Each player sacrifices all lands they control instead if seven or more cards are in your graveyard.

Risky Move

At the beginning of each player's upkeep, that player gains control of Risky Move.
When you gain control of Risky Move from another player, choose a creature you control and an opponent. Flip a coin. If you lose the flip, that opponent gains control of that creature.

Scrambleverse

For each nonland permanent, choose a player at random. Then each player gains control of each permanent for which they were chosen. Untap those permanents.

Winter Moon

Players can't untap more than one nonbasic land during their untap steps.

Back to Basics

Nonbasic lands don't untap during their controllers' untap steps.

Bend or Break

Each player separates all nontoken lands they control into two piles. For each player, one of their piles is chosen by one of their opponents of their choice. Destroy all lands in the chosen piles. Tap all lands in the other piles.

Rising Waters

Lands don't untap during their controllers' untap steps.
At the beginning of each player's upkeep, that player untaps a land they control.

Thieves' Auction

Exile all nontoken permanents. Starting with you, each player chooses one of the exiled cards and puts it onto the battlefield tapped under their control. Repeat this process until all cards exiled this way have been chosen.

Mountain

Island

Swamp

Possibility Storm

Whenever a player casts a spell from their hand, that player exiles it, then exiles cards from the top of their library until they exile a card that shares a card type with it. That player may cast that card without paying its mana cost. Then they put all cards exiled with Possibility Storm on the bottom of their library in a random order.

Warp World

Each player shuffles all permanents they own into their library, then reveals that many cards from the top of their library. Each player puts all artifact, creature, and land cards revealed this way onto the battlefield, then does the same for enchantment cards, then puts all cards revealed this way that weren't put onto the battlefield on the bottom of their library.

Worldfire

Exile all permanents. Exile all cards from all hands and graveyards. Each player's life total becomes 1.

Ruination

Illicit Auction

Each player may bid life for control of target creature. You start the bidding with a bid of 0. In turn order, each player may top the high bid. The bidding ends if the high bid stands. The high bidder loses life equal to the high bid and gains control of the creature. (This effect lasts indefinitely.)

Armageddon Clock

At the beginning of your upkeep, put a doom counter on Armageddon Clock.
At the beginning of your draw step, Armageddon Clock deals damage equal to the number of doom counters on it to each player.
{4}: Remove a doom counter from Armageddon Clock. Any player may activate this ability but only during any upkeep step.

Smokestack

At the beginning of your upkeep, you may put a soot counter on Smokestack.
At the beginning of each player's upkeep, that player sacrifices a permanent for each soot counter on Smokestack.