Rottenmouth Viper

As an additional cost to cast this spell, you may sacrifice any number of nonland permanents. This spell costs {1} less to cast for each permanent sacrificed this way.

Whenever Rottenmouth Viper enters or attacks, put
a blight counter on it. Then for each blight counter
on it, each opponent loses 4 life unless that player sacrifices a nonland permanent or discards a card.