Tron's threats like Maelstrom Colossus and Bramble Wurm are huge but slow to assemble, so the matchup is won by grinding card advantage rather than racing combat damage, making Tangle's extra effect of keeping attackers tapped less valuable than a steady blocker. Murmuring Mystic generates a growing army of flying tokens off your many instants and sorceries, giving you both blockers against their ground creatures and a long-game win condition. Very little of their maindeck is red (just Breath Weapon and Kaervek's Torch), so Hydroblast and Blue Elemental Blast have few targets, and Faerie Macabre has little to do, so they stay in the sideboard. Keep your remaining Fog effects since Maelstrom Colossus, Pinnacle Kill-Ship once it is stationed, and other big attackers still need to be neutralized in combat.