Because this was before the Master Rule 4 revision, they were locked out of the game, and the deck also used Topologic Gumblar Dragon to take 4 cards out of the opponent's hand
This allows you to bank spells for later, spread the mana cost over multiple turns , and, most importantly for Spider-Man 2099, cast those spells from exile
So, in a three-color deck built around red, white, and blue, aka the Jeskai colors, an Arid Mesa can fetch up a Raugrin Triome, which is a nonbasic land with the mountain, island, and plains types, and subsequently taps for all three corresponding colors
This has been helpful in my (and others') push to get more milling cards into the game
Meanwhile Red has access to a lot of targeted artifact hate - Manic Vandal, Ingot Chewer, and Oxidda Scrapmelter - and White has primarily access to the enchantment hate - Dawnbringer Cleric, War Priest of Thune, Wispmare
By detaching 2 XYZ materials from this card, you can halve the attack of any monster on the field and gain the attack lost