Just tossing out some ideas for individual missions for fun:
1. Frozen outpost - Our hero goes into a cold wilderness of rock and ice to look for and old outpost that hasn't been heard from in months, when he gets there
he discovers a wrecked installation and a mysterious archaeological site where unknown horrors await (perhaps something along the lines of Lovecraft's
Mountians of Madness and The Thing)
2. The mines - The Master Templar enters an abandoned mine that takes him deep underground where mysterious phenomena are going on to retrieve some
holy book or treasure left by his brothers in a previous expedition. (This wouldn't be a mission where fighting is involved, but rather a slow crawl through
haunted tunnels with lots of creepy phenomena - look up Bedtime Stories on Youtube
https://www.youtube.com/c/BedtimeStoriesChannel and
you can find lots of freaky ideas)
3. Terror in the Sea - A mission where the Order sends our guy to a fortress by the sea, he then goes to it's lower levels to enter a concrete lined tunnel that
stretches out under the sea floor for a long ways, finally connecting to a steampunk style underwater base that Jules Verne would be proud of. The
heretics have somehow found this place and have stormed it, trying to loot it for weapons and supplies. Of course it would be cool to see something BIG
eyeing you from the windows looking out onto the ocean.