Ambush!

The door behind you bursts open, and a tide of enemies pours through. Before you have time to draw breath, your blade is up, frantically parrying, as you try and recover from the shock of this unexpected assault.
Generate a new batch of Monsters using the Monster Tables for the appropriate Battle Level. Place these Monsters in the usual way. All of the Monsters generated have the Ambush special rule may therefore attack immediately. Take a treasure card as normal if they are defeated.