The 1st Edition packs and booster boxes are clearly marked with the "Edition 1" stamp
You have no guarantee going into a game that your opponent will be making use of any powerful artifacts, enchantments, or fliers so its best to keep cards like this out of your deck for game one and then bring them in for game two
Mishra wouldn't show up as a normal card until years later in Time Spiral when he finally got a legendary creature card
Magic: The Gathering | Avatar: The Last Airbender Eternal-legal sets (TLE) are Commander-, Legacy-, and Vintage-legal sets, and individual cards are also legal where already available in other formats
Not because Victini magically worked in that deck though, but because Vanilluxe was also glitched
The strength of Leyline of Resonance comes from being able to stack stat-boosts and spread powerful abilities to your primary attackers by giving them both effects like trample or double strike