Lord Leopold Baxten of Baldur’s Gate was a male human noble, archmage, and Magister of Baldur’s Gate, the highest position of magical authority in the city. He was killed by the Heroes of Phandalin in 807, Age of Tusks after attempting to seize control of the city with a force of Heartstone-mutated city guardsmen.
Leopold ruled the city of Baldur’s Gate as Magister alongside the Duke, his brother Francis Baxten. Using his position as Magister, and his talent for magical enchantment, Leopold had placed a magical stranglehold on the city, controlling the flow of magical items throughout the city, and placing heavy restrictions on the use of magic within the city walls. He had his own private guard – called “Spellbreakers” – which were equipped with specially-enchanted equipment to aid them in resisting and controlling magic-users. Heavy fines and penalties were levied against any people who broke these rules.
The party discovered that he and his brother had made an arrangement with the Cult of the Black Star and had been accepting shipments of Heartstone from them. By a cruel twist of fate, the mage’s spire and all of its inhabitants were poisoned by an accidental spill of Heartstone, killing most of them. In desperation, he managed to halt the disease in himself and a few surviving wizards, though at great cost…
Now corrupted by some dark influence within the Heartstone, Leopold took magical control of most of the city guard and made a move to take control of the city. The heroes were not able to reach him in time, and though he was defeated, his ritual was completed, transforming the corrupted city guardsmen into horrible monsters who began to lay waste to the city and its inhabitants, an event referred to as The Battle for Baldur’s Gate.