Black Sun's Zenith

Put X -1/-1 counters on each creature. Shuffle Black Sun's Zenith into its owner's library.

Call to the Grave

At the beginning of each player's upkeep, that player sacrifices a non-Zombie creature of their choice.
At the beginning of the end step, if no creatures are on the battlefield, sacrifice Call to the Grave.

Death Cloud

Each player loses X life, discards X cards, sacrifices X creatures of their choice, then sacrifices X lands of their choice.

Mutilate

All creatures get -1/-1 until end of turn for each Swamp you control.

Arena of the Ancients

Legendary creatures don't untap during their controllers' untap steps.
When Arena of the Ancients enters, tap all legendary creatures.

Damping Engine

A player who controls more permanents than each other player can't play lands or cast artifact, creature, or enchantment spells. That player may sacrifice a permanent of their choice for that player to ignore this effect until end of turn.

Storage Matrix

As long as Storage Matrix is untapped, each player chooses artifact, creature, or land during their untap step. That player can untap only permanents of the chosen type this step.

Contamination

At the beginning of your upkeep, sacrifice Contamination unless you sacrifice a creature.
If a land is tapped for mana, it produces {B} instead of any other type and amount.

Each player loses a third of their life, then discards a third of the cards in their hand, then sacrifices a third of the creatures they control of their choice, then sacrifices a third of the lands they control of their choice. Round up each time.