Mantaon was a great warrior and paladin long ago. But during his battles something changed in him. And he turned to evil ways. He became a conqueror. He became a destroyer of lands.
He was known to wield a powerful artifact called the Death Blade. It was a two handed pole arm with dual blades made from the metal of a fallen star. He wielded this weapon in battle and killed many powerful warriors with it in his hands.
Tomb of the Destroyer in a 5th Edition adventure for high level characters. Four to Six characters of 15th or higher level should find this adventure challenging as well as rewarding.