Jon Irenicus, Shattered One

At the beginning of your end step, target opponent gains control of up to one target creature you control. Put two +1/+1 counters on it and tap it. It's goaded for the rest of the game and it gains "This creature can't be sacrificed." (It attacks each combat if able and attacks a player other than you if able.)
Whenever a creature you own but don't control attacks, you draw a card.

Curse of Verbosity

Enchant player
Whenever enchanted player is attacked, you draw a card. Each opponent attacking that player does the same.

Steel Golem

Rotting Regisaur

At the beginning of your upkeep, discard a card.

Desecration Elemental

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
Whenever a player casts a spell, sacrifice a creature.

Plague Reaver

At the beginning of your end step, sacrifice each other creature you control.
Discard two cards, Sacrifice this creature: Choose target opponent. Return this creature to the battlefield under that player's control at the beginning of their next upkeep.

Demonic Taskmaster

Flying
At the beginning of your upkeep, sacrifice a creature other than this creature.

Phyrexian Negator

Trample
Whenever this creature is dealt damage, sacrifice that many permanents.

Hellcarver Demon

Flying
Whenever this creature deals combat damage to a player, sacrifice all other permanents you control and discard your hand. Exile the top six cards of your library. You may cast any number of spells from among cards exiled this way without paying their mana costs.

Thought Reflection

If you would draw a card, draw two cards instead.

Abyssal Persecutor

Flying, trample
You can't win the game and your opponents can't lose the game.

Rust Elemental

Flying
At the beginning of your upkeep, sacrifice another artifact. If you can't, tap this creature and you lose 4 life.

Lord of the Pit

Flying, trample
At the beginning of your upkeep, sacrifice a creature other than this creature. If you can't, this creature deals 7 damage to you.

Greater Harvester

At the beginning of your upkeep, sacrifice a permanent.
Whenever this creature deals combat damage to a player, that player sacrifices two permanents of their choice.

Negate

Counterspell

Ebonblade Reaper

Whenever this creature attacks, you lose half your life, rounded up.
Whenever this creature deals combat damage to a player, that player loses half their life, rounded up.
Morph {3}{B}{B} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)