Andergard

Dealing damage to a player's life total is insignificant compared to the power of dealing damage to a player's actual, real-world time.

In the sense that once you learn it, you never forget how to do it? And just like bicycling, "It's good for you!"

Why is that a "rumour"?

Richard Garfield was a doctoral candidate at University of Pennsylvania when he first started to design the game. During his free time he worked with local volunteer playtesters to help refine the game. He had been brought on as an adjunct professor at Whitman College in 1991 when Peter Adkison (then CEO of Wizards of the Coast games company) first met with Garfield to discuss Garfield's new game RoboRally

Adkison saw the game as very promising, but decided that Wizards of the Coast lacked the resources to produce it at that point. He did like Garfield's ideas and mentioned that he was looking for a portable game that could be played in the downtime that frequently occurs at gaming conventions. Garfield returned and presented the general outline of the concept of a trading card game. Adkison immediately saw the potential of this idea and agreed to produce it. Magic: The Gathering underwent a general release on August 5, 1993.

Source - Wikipedia: 'Magic: the Gathering', specifically under 'History'. Includes sources.