Eldrazi Tron has supplanted the traditional G/X Tron versions because it's able to operate effectively without Tron while still being overpowering with it, thus making it similarly explosive to the old style lists while also being more resilient to the common hate.
But before we had the Eldrazi, there was a Mono-Blue variant of Tron that operated on a similar principle. Cards like Remand and Repeal could function as early interaction should you need time to assemble Tron or simply need a way to not die to fast combo decks. Importantly, those spells cantrip, effectively digging you toward Tron much like Chromatic Star and Chromatic Sphere did, so you don't lose much if anything in consistency.
With TitanShift and Storm ascending into the top tier in the Modern metagame, that early interaction looks a lot better, and it's not hard to incorporate the blue cards into a typical Eldrazi Tron list.
Of course, because this list is a bit better at assembling the Urzatron than traditional Eldrazi Tron, it's best to incorporate an additional way of taking advantage of it. Ulamog, the Ceaseless Hunger is perhaps the most powerful effect you can reasonably cast, and in order to enable it, this list plays Conduit of Ruin over the more common Reality Smasher.
With Tron active, you can almost always curve the two cards into each other, leading to plenty of games that are close until you blow them wide open around turn 4 or 5. You still have the powerful early plays of Walking Ballista, Thought-Knot Seer, and Matter Reshaper, but you're now better at going over the top, thus getting the best of both words from traditional Tron and Eldrazi.
Repeal also gives the deck a fantastic catch-all answer to things like Stony Silence that Tron decks have previously lacked. The deck is powerful enough that opening a one-turn window is often all you need to put the game away, so Repeal is the perfect tool for the job, not to mention its ability to disrupt aggressive decks.
The one downside here is that your manabase is less consistent by adding a significant color, but there's a lot to gain from that sacrifice.
- 3 Walking Ballista
- 4 Conduit of Ruin
- 4 Matter Reshaper
- 4 Thought-Knot Seer
- 2 Ulamog, the Ceaseless Hunger