Ghostly Prison

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Pendrell Mists

All creatures have "At the beginning of your upkeep, sacrifice this creature unless you pay {1}."

Forced Fruition

Whenever an opponent casts a spell, that player draws seven cards.

Phyrexian Arena

At the beginning of your upkeep, you draw a card and you lose 1 life.

Guardian Project

Whenever a nontoken creature you control enters, if it doesn't have the same name as another creature you control or a creature card in your graveyard, draw a card.

Bitterblossom

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

Rhythm of the Wild

Creature spells you control can't be countered.
Nontoken creatures you control have riot. (They enter with your choice of a +1/+1 counter or haste.)

Inexorable Tide

Whenever you cast a spell, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Blood Moon

Tribute to the World Tree

Whenever a creature you control enters, draw a card if its power is 3 or greater. Otherwise, put two +1/+1 counters on it.

Doubling Season

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.
If an effect would put one or more counters on a permanent you control, it puts twice that many of those counters on that permanent instead.

Mana Reflection

If you tap a permanent for mana, it produces twice as much of that mana instead.

Price of Knowledge

Players have no maximum hand size.
At the beginning of each opponent's upkeep, Price of Knowledge deals damage to that player equal to the number of cards in that player's hand.

Exquisite Blood

Whenever an opponent loses life, you gain that much life.

Swarm Intelligence

Whenever you cast an instant or sorcery spell, you may copy that spell. You may choose new targets for the copy.

Mind Over Matter

Discard a card: You may tap or untap target artifact, creature, or land.

Yawgmoth's Bargain

Skip your draw step.
Pay 1 life: Draw a card.

Fervent Charge

Whenever a creature you control attacks, it gets +2/+2 until end of turn.

Shark Typhoon

Whenever you cast a noncreature spell, create an X/X blue Shark creature token with flying, where X is that spell's mana value.
Cycling {X}{1}{U} ({X}{1}{U}, Discard this card: Draw a card.)
When you cycle Shark Typhoon, create an X/X blue Shark creature token with flying.