“ A certain type of demon cannot not be hit by ranged weapons or attacks. Attacks have to be made up close and personal for the damage to mean something. Ranged attacks are to impersonal.
Possibally a way to make the ranged attacks more meaningful would be to coat the arrow head or what not with the shooters blood. Of course, they'd better be a good shot, otherwise they're wasting arrows and already bleeding to boot.
Spells: wizards might have half or no effect, preist might work due to divine intention.”
“ To purify the water from a certain river the monks have carved a section of the river that goes over a stone bed. Through holy carvings of gods, godesses, and holy symbols and then the river flowing over them, it purifies the water making it safe for drinking and/or makes it holy water. For rivers that do not have natural rock bottoms, large smooth stones can be carved and added to the water to fully cover the bottom.”
“ The lengthy process to do something necessary or a magical scroll needed is inscribed on the other side of a great tapestry and can't be removed. For more fun it could be in the kings throne room. Try to hide in shadows with a 20*5 (yards/meters) monstrosity!”