Budget U Tron for the masses.
Are you looking for a highly competitive, tuned, deck that will win PTQs? This list isn't for you. If you want that, feel free to check out my wife's full fledged Tron list here: I Fight For the Users!
Are you new to modern? A control player? Looking to try out Mono Tron? Playing on a budget? Looking for a list to give to a friend who is new? Then this list is for you.
The goal here is to start with a budget base and replace the stand in cards like
Scuttling Doom Engine
with the cards in the maybe board like Wurmcoil Engine. You can work up into the staples of this deck as you go 1 for 1.
The next segment covers what to upgrade as far as priority.
Wurmcoil Engine-
Scuttling Doom Engine
Handle this first, these guys aren't TERRIBLY expensive due to commander reprints. You really need the lifegain against some decks. A resolved Engine will break the back of a lot of decks.
Remand-Mana Leak
This is the second thing you need to get. O-Stone can wait a little bit since you can still use Perilous Vault for nearly the same total mana. Downside is, you can't spare things from the Vault. Remand is a good counter in any stage of the game whereas Mana Leak is very bad in the late game where you want to start winning.
Oblivion Stone-Perilous Vault Get this last. It's EXTRAORDINARILY good with most of your deck but truth be told, Perilous Vault works in a lot of cases. O-Stone gives you the ability to NOT kill specific things. That pays for itself in spades.