Squish, Squish. Squish.
Bogmoors has been here for 721 years. It started with an ale stop for the Imperial invaders. From there it has been a similar stop for every wave of invaders since then, as well as every local for a good walk’s distance.
Believable magic, like ordinary physicis, operates according to some invariable laws that always result in some kind of cost or "bounce back". The grater the magic, the more it should cost the character physically, emotionally, and spiritually.