Granted. A platter of cookies appears before you. They are the most delightfully delicious cookies ever created. They also cause instant death upon consumption. The glass containing the milk is shatter-proof and has no lid.
I wish, with complete control on my behalf, to be perfectly fluent in every dialect of every language, real or made up. This applies to both written and spoken languages and does not cause any diminished performance of my senses, cognitive functions, or other abilities.