"This sort of innovation occurs when you set out to improve an electric tea kettle and misplace a decimal."

Cosmotronic Wave

Cosmotronic Wave deals 1 damage to each creature your opponents control. Creatures your opponents control can't block this turn.

Ravnica: Clue Edition

The List

Guilds of Ravnica

Because Cosmotronic Wave doesn’t change the characteristics of any permanents, the set of creatures affected by its second effect is constantly updated. Creatures that come under an opponent’s control later in the turn can’t block.