Rex, Cyber-Hound proves a Fallout robot dog can steal abilities

Rex, Cyber-Hound arrived with Magic: The Gathering - Fallout on March 8, 2024, part of a line of four ready-to-play Commander decks. The legendary artifact creature - Robot Dog looks like a novelty commander at first glance, but it turns graveyards into a toolbox and energy counters into the fuel that keeps the whole machine moving.

Rex is an engine, not a mascot

The first thing to understand is that Rex does not care about flashy stats. Its combat damage trigger mills two cards and gives you two energy counters, which is exactly the kind of small, repeatable burst that adds up when the deck is built correctly. Then Rex can spend two energy to exile target creature card from a graveyard with a brain counter on it, and from there it gains all activated abilities of the cards it has exiled this way.

Rex gets activated abilities, not triggered abilities or static abilities, so you are not just raiding graveyards for whatever looks powerful. You are looking for tap abilities, mana abilities, repeatable utility, and activated text that can be turned into a resource advantage. If a borrowed activated ability names the original card, Rex’s version refers to Rex instead.

Once the ability is activated and the cost is paid, it is too late to stop the activation by removing the creature card from the graveyard. In practice, that means Rex rewards you for acting at the right window and punishes opponents who assume they can sandbag interaction until the last second.

Feed the dog before you ask it to work

Rex only pulls ahead if you make combat damage connect consistently. The deck wants those two energy counters every turn cycle, and if Rex gets stonewalled by a random blocker, the whole plan slows down. Whispersilk Cloak is exactly the kind of blunt, efficient tool this commander wants, because it gives Rex a clean attack lane and keeps the combat-damage trigger firing.

Delney, Streetwise Lookout does a different job, but it is just as valuable. Previewed on February 6, 2024 in Murders at Karlov Manor, Delney comes out of the Tenth District. In this shell, it helps creatures get through and increases the value of your triggers, which is a nasty fit when your commander wants to attack, connect, and keep harvesting energy. Wizards later used Delney in another story deck for the same support role.

The graveyard has to stay full

Rex is strongest when there is always another target waiting in a graveyard. If you are only relying on what opponents have already dumped, you are giving up too much control over your own game plan. The cleaner approach is to run repeatable mill and wheel effects so graveyards never run dry.

Ghoulcaller’s Bell is a good low-friction example because it keeps stockpiling targets over time. Windfall does the heavier lifting, refilling hands while dumping a fresh batch of cards where Rex can reach them. That combination does two jobs at once: it loads enemy graveyards for Rex to raid and gives you a steady stream of activated abilities to choose from. It also means the deck does not fold if a single graveyard gets picked clean, because there is always another pile forming.

The best stolen abilities are the ones that snowball

Once Rex starts collecting activated abilities, the deck gets a lot broader than a simple graveyard-hate package. Illusionist’s Bracers is the kind of card that can turn an already useful activation into a real payoff, because copying activated abilities makes Rex’s stolen text more dangerous fast. The Enigma Jewel and Thousand-Year Elixir also do important work here, letting the robot dog make better use of the powers it has exiled.

You are not just trying to cast good cards. You are assembling a set of repeatable activations that scale with energy, combat damage, and whatever Rex has stolen so far. A stolen mana ability or card-draw engine pushes that plan much harder.

Rex also does not need to wait around for opponents to hand over all the good toys. The deck can run its own mana dorks and draw creatures, including Omen Hawker and Arcanis the Omnipotent, so you can keep the engine moving even when graveyards are sparse or opponents are playing cautiously.

The combo finish is where it gets real

With Pili-Pala and Palladium Myr, Rex can generate infinite mana by exiling both creatures, tapping Rex for two, then paying two to untap and repeat the loop. The line works because Rex can steal the relevant activated abilities and recycle them.

There is another line that pushes in a different direction. Trench Behemoth plus Walking Atlas creates infinite landfall triggers, which can become a Ruin Crab or Altar of the Brood kill. If the bounced land enters untapped, that same setup can even produce infinite mana.

Why Rex outgrew the novelty label

The Fallout Commander decks were built as ready-to-play 100-card precons, and the set itself leans into Fallout history going back to 1997. Its mechanics use energy counters, graveyard exile, and ability reuse.