Eldrazi Tron is almost entirely built on nonbasic colorless lands (Urza's Mine, Urza's Power Plant, Urza's Tower, Eldrazi Temple, Ugin's Labyrinth), so Magus of the Moon is devastating, turning their entire manabase into Mountains and shutting off their colorless mana engine. Obsidian Charmaw gets discounted for each of their colorless-producing lands, often costing just 1-2 mana, while also destroying a key nonbasic land such as Urza's Tower or Eldrazi Temple and providing a flying clock they struggle to answer. Fatal Push is trimmed since most of their threats (Emrakul, Ugin, Karn) are too large or noncreature to hit; Village Rites and Corrupted Conviction are cut as they don't help race or disrupt this grindy prison matchup.