All that is known about Tiberyl the Terrible is that an adventurer, who had been challenged by Bozbik the Face Breaker during the Great Monster Uprising, discovered and defeated the evil, sentient bell known as Tiberyl the Terrible in his mad rush to raise the funding required to purchase a weapon that might give him a chance at defeating Bozbik in the arena.

SOURCE(S): Legends of Zork (personal correspondence from the author of 'Enter the Face Breaker' quest)