The Trials of Initiation are a series of trials for Vampires to take part in. They have to complete five of them in order to succeed. They are usually taken by those training to become a Vampire General or a games master like Vanez Blane. Failure to complete a trial results in death at the Hall of Death. At one point in the past, these were required to be done by every vampire who went to the mountain for the council. There also seem to be old loop-holes for preperation and extra practice time that were used to help Darren Shan prepare for his own trials; most vampires disregarded these in the present to emphasise their own strength, but there is nothing dishonorable about bringing them back.
There were originally over thirty trials, but when Darren competed the Princes restricted themselves to only choosing from seventeen trials, dismissing others as they either lacked the resources to carry them out at this time- such as the Pit of Snakes being impossible due to a lack of snakes- or because it would have been impossible for Darren to complete them due to his half-vampire status putting him at a disadvantage due to his lesser speed or strength.