Sick of getting your lands blown up when you're playing G/R Tron? Perhaps you need a backup plan. Is killing all of your opponent's permanents a reasonable strategy? I certainly wouldn't mind giving them a taste of their own medicine.
This deck foregoes Karn Liberated for a little more explosiveness. Sundering Titan and Ugin, the Spirit Dragon cost eight instead of the magical number of seven, but Wall of Roots and Simian Spirit Guide assist with that. If you're not able to set up Tron because of disruption or a draw that didn't pan out, Wall of Roots and Simian Spirit Guide can also help cast an early Through the Breach.
Even you don't have Tron, your opponent likely won't have many permanents (or life points) after an Emrakul, the Aeons Torn connects. In a pinch, Sundering Titan can sub in. If you're facing down a Burn deck, perhaps Wurmcoil Engine is the correct creature to put onto the battlefield, even if it's less explosive.
Chromatic Sphere finally joins Chromatic Star in the deck, but it's more out of necessity than anything. Wall of Roots needs to be cast on turn two, and either artifact is perfects for accomplishing that. Once Wall of Roots is on the battlefield, you should have no trouble finding green mana.
I like this deck because, although it gives G/R Tron more ways to be inconsistent, it also allows the deck to keep a wider range of hands which had previously been a problem. The Through the Breach package also gives you a way to beat combo decks or decks that were typically faster than Tron. Decks like Affinity could beat a turn-three Karn or Wurmcoil, but they can't really beat a turn three or four Emrakul attack.