No Mercy

Whenever a creature deals damage to you, destroy it.

Vedalken Orrery

You may cast spells as though they had flash.

Praetor's Grasp

Search target opponent's library for a card and exile it face down. Then that player shuffles. You may play that card for as long as it remains exiled.

Maralen of the Mornsong

Players can't draw cards.
At the beginning of each player's draw step, that player loses 3 life, searches their library for a card, puts it into their hand, then shuffles.

Bitterblossom

At the beginning of your upkeep, you lose 1 life and create a 1/1 black Faerie Rogue creature token with flying.

Dark Confidant

At the beginning of your upkeep, reveal the top card of your library and put that card into your hand. You lose life equal to its mana value.

Darkness

Prevent all combat damage that would be dealt this turn.

Rise of the Dark Realms

Put all creature cards from all graveyards onto the battlefield under your control.

Animate Dead

Enchant creature card in a graveyard
When Animate Dead enters, if it's on the battlefield, it loses "enchant creature card in a graveyard" and gains "enchant creature put onto the battlefield with Animate Dead." Return enchanted creature card to the battlefield under your control and attach Animate Dead to it. When Animate Dead leaves the battlefield, that creature's controller sacrifices it.
Enchanted creature gets -1/-0.

Meekstone

Creatures with power 3 or greater don't untap during their controllers' untap steps.

Polluted Bonds

Whenever a land an opponent controls enters, that player loses 2 life and you gain 2 life.

Saw in Half

Destroy target creature. If that creature dies this way, its controller creates two tokens that are copies of that creature, except their power is half that creature's power and their toughness is half that creature's toughness. Round up each time.

Entomb

Search your library for a card, put that card into your graveyard, then shuffle.

Infernal Genesis

At the beginning of each player's upkeep, that player mills a card. Then they create X 1/1 black Minion creature tokens, where X is the milled card's mana value.

Mindslaver

{4}, {T}, Sacrifice Mindslaver: You control target player during that player's next turn. (You see all cards that player could see and make all decisions for the player.)

Tainted Aether

Whenever a creature enters, its controller sacrifices a creature or land of their choice.

Reanimate

Put target creature card from a graveyard onto the battlefield under your control. You lose life equal to its mana value.

Ensnaring Bridge

Creatures with power greater than the number of cards in your hand can't attack.