Thelon

Thelon of Havenwood was an elven druid from Sarpadia during the Fallen Empires period of Dominaria's Dark Age.

Thallid Creation
As conventional foods such as fruit and animals were becoming increasingly scarce due to the changes in climate following the Sylex Blast, Thelon made it his task to find a new food source. He found that the only things that were successfully growing were fungus, which he decided to vigorously cultivate using green mana and a method similar to that which the Order of the Ebon Hand used create the thrulls. Calling them thallids, they were raised like cattle to produce saprolings for food.

Thelonite Order
This saved the elves of his native Havenwood from starvation and led to the creation of an order of elves, humans, and sentient insects that may have been nantuko called the Thelonites. The Thelonites were druids and monks who used blood sacrifices in order to bring about new life. The saprolings generated by the thallids made excellent fodder for their practices.

Thallid Revolution
Thelon's miracle was short-lived, as over time the thallids grew sentient and aggressive. Debate raged among the elves over whether or not they were truly intelligent and how to treat them. This rift at its most heated was headed by the Thelonite druid Morgan and the master scout Loren. Morgan believed the thallids nothing more than fodder for food and cultivation, and would eventually ambush and kill Loren. Loren's death would further widen the rift between the two elven factions, allowing for the thallids to overrun all of Havenwood in almost a single day.

The Future
Thelon's specific fate is unknown, but it is likely that he was amongst those killed by the thallid swarm. Thousands of years after the fall of the elves, a reflection of Thelon, like many other historical figures, came into existence due to the ravaging rifts in time in Dominaria's post-apocalypse era. There he would bear witness to the death of all Dominaria, but would also see his thallids thriving in the apocalyptic wastes. The Great Mending caused the return to Thelon to his original timeline.

Trivia
The card name of Thelonite Monk is likely a play on the name of jazz musician Thelonious Monk.