Maxe

My trainer always told me, even after years of training, that the first choice should always be running away instead of engaging.

Dispel Magic is the worst offender in my opinion. Imagine you spend one year casting the same spell at the same location, every day, so that it can become permanent. And then one green adventurer stumbles into your dungeon and tries out this new “Dispel Magic” spell he just learned. All your hard work and components gone.