Into the Dungeon

Into the Dungeon has Flash as long as an
opponent controls a Legendary permanent.
All nonland permanents on the battlefield are returned to their owner's libraries. Each player
then shuffles their library.
If you controlled one or more Adventurers before
you cast this spell, you may then draw a card.
(Adventurers are creatures with the subtype Warrior, Rogue, Wizard, Monk, and/or Cleric.)