There are six rules regarding trading with monsters.
Rule #1: Get a good night’s sleep before you cast your protection circle. If you nod off even once, the last thing you’ll ever see is sharp teeth.
Rule #2: Decide on exactly what you want to trade. Haggling weakens the protection circle and, well, refer to Rule #1.
Rule #3: If you’re dealing with a hungry monster, you may have to agree on a limb deal, so decide which arm is not your favorite beforehand, and bring a second wizard to remove the limb, cauterize the stump, and, of course, keep up the protection circle because you’ll be unconscious from the pain. And please don’t trade a leg, no matter what the monster offers. They never want just the leg.
Rule #4: After the monster agrees to the trade, slide your offered object out of the protection circle with a stick or broom, not your hands, or the monster will understandably assume that you’re throwing in your hands as a bonus.
Rule #5: Wait for the monster to leave the area before you get what you came for. And by leave, I mean, at least ten miles away, not invisible, hiding in a pocket dimension, merged with stone, burrowed underground, or looking like your mother with impressive canines.
Rule #6: After you acquire your trade and are safely home, make a huge offering to the gods for letting you get away with trading with a monster, because that’s a really stupid thing to do.