Rottenmouth Viper Aetherdrift and Rats you control get

and Rats you control get +1/+1 until end of turn

put a flood counter on target land

put a loyalty counter on Ral

choose one that hasn't been chosen this turn —

or Nightmare costs {1} less to cast

Rottenmouth Viper Aetherdrift and Rats you control getAs 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 this creature 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 of their choice or discards a card.