A Three-Round AD&D Game Tournament
The 1998 AD&D Game Open Tournament
From the introduction:
It all started with the end of the world. At least, that is what it looked like until your mentor Askinn told you about his crazy plan. One last ditch effort to save the world, he said. “You must go back into the past, and find the source of the knowledge of time travel. Then you must eliminate that knowledge permanently from the world.” So he said, and so you go. Since the world is ending, there is nothing to lose in trying, even though what you know of time travel indicates that this plan should not work. Somehow the knowledge will get into the world.