Tron has no blue cards, so Pyroblast and Red Elemental Blast stay in the board; instead Smash to Smithereens is a strong proactive answer to their numerous artifacts (Expedition Map, Barrels of Blasting Jelly, Bonder's Ornament, Pinnacle Kill-Ship, Giant's Boulder) while also dealing relevant damage to the opponent's face. Relic of Progenitus can exile their graveyard to blunt Bramble Wurm's graveyard lifegain and Haunted Fengraf's recursion, though its main role here is incidental disruption since Tron's engine is mostly board-based. We want to race before Urza's Tron assembles and casts Maelstrom Colossus or Unfathomable Truths, so trim the slowest value cards for proactive artifact removal.