There are three waves of monsters in the area, scaled to check as "Decent Challenge" , "Even Match", and "Tough" for the lowest level party member. They aggressively attack players who do not have appropriate Sneak or Invisible status. Higher-leveled players will not catch aggressive behavior if the monsters check too weak.
Three to four monsters from within each wave will instantly head for the startpoint. As long as all monsters remain alive, no more monsters will spawn. As soon as a monster dies, a new one will come from its original spawn point. If the monsters are killed unevenly, you can force individual spawnpoints to run out, and engage fewer enemies at a time within the each wave.
If you wish to do so, it is possible to move away from the centre in order to avoid aggro from approaching monsters. You can then pull and fight monsters one at a time.
Once a wave is wiped out, a ??? will appear on the ground giving whoever touches it a Temporary item. The next wave's monsters are instantly spawned and begin to head for the center. The normal maze has 3 waves. Trial by Numbers grants a 4th wave.