Madse, Confidant of Ashiok

Prevent all damage that would be dealt by
Madse, Confidant of Ashiok.
Whenever a Nightmare leaves the battlefield or attacks, each player puts the top X cards of their library into their graveyard, where X is that
creature's power.
Whenever a Horror leaves the battlefield or
attacks, each player puts the top X cards of their library into their graveyard, where X is that
creature's power.