There are currently 13 bosses in DemonCrawl.
Bosses roam the board in the same way as familiars but will only walk into opened cells and will not solve cells. If any cell they enter contains loot or a familiar, the boss will destroy it.
Bosses are random for each quest with two exceptions. In Beyond, the Computer Simulation emblem guarantees Beyond Ego and in normal mode, the player's first completion of Shadowman will always be Ego.
When on a boss stage, special loot called Dark Hearts spawn. These empower the boss in unique ways. Making a mistake in a boss level will spawn additional dark hearts as well as, for most bosses, triggering an additional undesirable effect.
You are able to kill bosses by freezing or exploding them. Ego is an exception and can only be exploded. All bosses resist burning. Having full health along with Midas Glove turns all Dark Hearts into Diamonds, making bosses much more predictable. Similarly, Iron Sceptre can clean up unwanted dark hearts without the need to collect them. Uncovering a corner cell as the first cell but then starting to solve elsewhere on the board (using something like Spy gleaning, a Longbow or Wand Of Light to safely make a start elsewhere) will leave a boss confined to a small area of the board, leaving the player to solve the level in relative safety.
Gain a random omen whenever a Dark Heart is collected.
Switches between the following effects randomly every turn:
Switches between the following effects randomly every turn triggered when you make a mistake or a dark heart is collected:
Seal your first available inventory slot when a Dark Heart is collected.
Spawn 2 Dark Hearts whenever a Dark Heart is collected.
Lose a random item whenever a Dark Heart is collected
Spawn a Harbinger whenever a Dark Heart is collected.
Lose 100 mana whenever a Dark Heart is collected.
Whenever a Dark Heart is collected, you take 1 damage.
Every minute, take 3 damage.
Conceal a random cell every time a Dark Heart is collected.
Spawn 3 cankers whenever a dark heart is collected.
Uncomplete the first stage.
Spawn a Bagman whenever a Dark Heart is collected.