The Battle Phase consists of at least one round. Each hero takes a turn, and then the Overseer takes one turn for each monster in the room. (One turn counts as one action any character takes.) A round is complete when all heroes and all of the Catacomb Lord’s Forces have taken one turn.
When all monsters in the room have been destroyed, frozen, or a combination of the two, the room is complete and the Battle Phase ends. All heroes are freed from Devoured and Teleported cards. All Stunned cards are removed. All other pieces — such as obstacles, shields, and fire walls — are removed from the playmat.
If at least one hero survives the Battle Phase, the Resolution Phase begins.