Originally posted by High Octane Wildebeest:

How many total secret bosses are there? I've located four of them, being the ones in the towers.
Veno drops agility tome, Tusk drops cheese, Silencer drops intelligence tome, and sandking drops tome of strength. Are there any more secret bosses in the game, and if so how are they found? Does the enemy fountain actually do anything important?

no. that's all. i think there should be an invisible secret boss some where :D

There should be a secret boss that is unlocked once the four towers and bosses are defeated. The enemy fountain becomes vulnerable and you can destroy it to fight a super boss. No idea what it would drop or what the fight would entail.

Enemy fontain will drop mega rapier or some thing like that (i dont know)

Since gem of true sight is now dropped by tusk rather than purchased, there should be a secret boss that is permanently invis and wanders around the map and spawns when the other four bosses are defeated. Doesn't actively attack towers or players, but when aggroed it is very deadly. Possible Riki that wanders around, or a stationary Templar, or any invis hero that hasn't already been used. They drop either a unique item, or they can drop an early sapphire.