Traumatize by paying ({3} magic symbol) ({U} magic symbol) ({U} magic symbol) , causing a player to mill half their library, rounded up.
Activate
Riverchurn Monument's exhaust ability by paying ({2} magic symbol) ({U} magic symbol) ({U} magic symbol) and tapping it, causing each player to mill cards equal to the number of cards in their graveyard, thus causing the player targeted by