Toxic Deluge

As an additional cost to cast this spell, pay X life.
All creatures get -X/-X until end of turn.

Sol Ring

Day of Black Sun

Each creature with mana value X or less loses all abilities until end of turn. Destroy those creatures.

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Tariel, Reckoner of Souls

Flying, vigilance
{T}: Choose a creature card at random from target opponent's graveyard. Put that card onto the battlefield under your control.

Swamp

Mountain

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Exotic Orchard

{T}: Add one mana of any color that a land an opponent controls could produce.

Plains

Damn

Destroy target creature. A creature destroyed this way can't be regenerated.
Overload {2}{W}{W} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")