Looking at what everyone has put here, i think i may have a solution that works off of what the Zenko already has, and create a more interesting RP aspect for those who are the magicy type as well as to bring others to the Zenko grounds itself.
The Zenko's Main role as protectors from the Face is for now, a 2nd priority, Instead, they now have to focus on the Corruption of the land. Tass. Although Tass is known for being a source of Raw magic, it is still poisonous and spreading, but other then that, the Tass is still mostly unknown. So the Zenko now have to focus on Containing and Researching it.
However, for the past however many years, the Zenko has existed as a military faction, focused solely on protecting Zenko and Lismore from the threats of the portal, due to this they are ill equipped to Study the Tass fully, and so the Call for Magi, priests, Scholars, anyone who maybe able to study and help contain and understand the Tass has been made.
(Note: This next part i would like to have done ICly, if this is to be taken on board)
The Current Alchemists of the Zenko, to help make this task easier, have found a way to combat the Atmospheric Tass Poisoning people can contract by being on the grounds. Using the blood from the Already mana corrupted Members of the Zenko, they have made a potion able to immunise those visiting the lands from its effects, despite this, the drinking of Tass Water is still poisonous and not recommended.
If left unchecked the Tass may spread across the island and make it uninhabitable, and so the Task falls onto the Zenko to make sure this doesn't happen.