Destroy target creature. Create two Treasure tokens. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")
If the target creature is an illegal target by the time Contract Killing resolves, the entire spell doesn’t resolve. You won’t get Treasures. If, on the other hand, the target is a legal target but isn’t destroyed (most likely because it has indestructible), you’ll get Treasures.