You don't always fight monsters. Most events will probably be humanoids and magic will work on those. There are some spells that works on monsters.
There is a risk using magic, but this isn't a d&d-like game, magic should be used with caution. There are also safe castings.
Me and my group have 38 (long) sessions with FbL and besides that a demon was summoned one time, nothing really that harsh has happen with magic mishaps, both for the reason that my players know to only use spells when you actually are needing it and the use of safe casting.
“I’d say thistles, but nobody listens to me, anyway.” - Eeyore