cynthialee wrote:1 or 2 Snitch dudes in play would be all you need.
If the dungeon is built with the Snitch Villain mechanic taken into consideration the game could be well enough balanced.
Stock the rooms with slow monsters, so as they are released they slowly start making their way to the heroes in a seemingly unending line of monsters.
If playing the Chaos Tokens mod (what can potentially spawn a snitch, Special Character) the snitch is auto counter balanced. Using the snitch to open all the rooms early on will reduce/remove the ability to play certain tokens that might be drawn later on, Trap tokens and more Special Character tokens. These can be more devastating than a slowly advancing mob.