The Magic Elixir is a medicinal potion that can heal any illness. Duke and Gameboy had to travel to Faxanadu to find it when Kevin Keene contracted a video virus.
Dr. Wright told the N Team that they needed Kevin's magic mantra to administer the elixir. Simon Belmont suggested that it was related to Princess Lana, and she found out that he was right when she successfully administered the elixir and healed Kevin.