Today, the name of Magic: The Gathering is iconic in terms of gaming and geek culture. It's one of the few playing card games to successfully enter pop culture and, really, can you see it as anything but that at this point?
Well, for a time in the early 1990s, this new Magic collectible card game just wasn't going to work. You see, right after Richard Garfield and friends had started revamping their Five Magics game, they had finally settled on a name: Magic. Literally, just Magic. Short and sweet. Simple. To the point.
All they had to do was copyright that name, right? Wrong.
A lawyer essentially told them that copyrighting a word as broad as "magic" would be like copyrighting the word "water" or "the" (we're looking at you, Ohio State University). In short, they needed a new name for the game - one that was a bit more robust and unique than simply Magic. After many back and forths, they finally decided on Mana Clash.
As cool as the name was, however, everyone from play testers in the east to the Wizards of the Coast crew on in the Pacific Northwest, still simply referred to the game as Magic. To them, there was no other word to describe it.
With art and printing dates looming, they went back to the lawyer and asked what they could do to keep Magic, well, Magic. As it turns out, what they needed was a second part; something to discern it from the base term and something unique enough to get that all important copyright.
After even more debate, the words "The" and "Gathering" were decided upon. At least, it was decided that the addition of "The Gathering" would work for this first round of cards. Thus, Magic: the Gathering came into being.
That wasn't the end of the story, however.
With what is more-or-less a sequel or edition name now attached to the word "magic," Garfield's intent was that each new set would have a new name. Like with the already-planned set Ice Age, it wouldn't be Magic: The Gathering - Ice Age. Rather, it would be Magic: Ice Age. with each expansion getting its own completely unique name over and over again. Even the card backs were to be different colors from the base brown we've all become beyond familiar with, such as the card backs for Arabian Nights employing a purple-ish color scheme.
Once again, though, fate seemed to nudge again towards keeping with MTG.
The lawyer once again pointed out that the copyright needed to stay valid, and it would be a massive headache for the actual game itself to keep changing it's name each year. It would be like Monopoly switching to Monopoly: Boardwalk or Monopoly: Gangland 1920's each year. So the name Magic: The Gathering was kept as-is and has remained firmly in place ever since. Plus, the fanbase really, really liked it.
As for Mana Clash, the name did, indeed, make it into the game courtesy of the 1994 set The Dark and a reprint in each of the game's core sets from Fifth Edition through Ninth Edition.