While traveling trough farm land the PCs come upon a merchant sitting on a wrecked wagon without a mule attached to it, hid face burrowed in his hands. He explains that he was robbed by petty goblins, unable to defend himself he had retreated. He asks the PCs to help him retrieve the mule before the goblins roast it, as a reward they may keep his goods. How hard can it be?
Magic should have side effects, both expected and unexpected - fortuitous and deplorable. Expected side effects add anticipation, while unexpected ones increase the drama of the scene. The result can be comedic or dire, it dpends on which circumstances work best for your game.