Moon Stompy has always seen play in Legacy as part of the "Blood Moon trio," along with Imperial Painter and Mono-Red Sneak Attack, but after the printing of Chandra, Torch of Defiance and the banning of Sensei's Divining Top, Moon Stompy is the leader of the pack.
This deck is capable of amazing starts, and can lock an opponent out of the game from the very early turns.
Chalice of the Void, Ensnaring Bridge, Trinisphere, Blood Moon, and Magus of the Moon make life very hard on your opponent, especially when those come down very early with mana acceleration like Chrome Mox, Simian Spirit Guide, and with Sol lands like Ancient Tomb and City of Traitors.
Here's my list and how I got here.
The core of the deck is in its prison elements: Blood Moon, Magus of the Moon, Chalice of the Void, Ensnaring Bridge, and Trinisphere. From there, you have a lot of space to choose which creatures you'll use to win the game.
Chandra, Torch of Defiance is the planeswalker that pushed this deck over the top, and it's a 4-of in every Moon Stompy list. It's so versatile, able to draw cards, ramp mana, kill creatures and kill your opponent. It's everything you need.
Koth of the Hammer is a much worse Chandra since it can add mana at a much higher cost (-2 rather than +1) and its +1 ability is clunky when you have Ensnaring Bridge out, though its emblem wins game quickly and is why I like it as a 1-of.
Quicksmith Rebel is a spicy one. It's able to not only kill your opponent once the board stalls, but also kills your opponent's creatures if you don't have Ensnaring Bridge out, or annoying planeswalkers.
Hazoret, the Fervent might look fantastic as this deck is almost always empty handed, but when I tried it, it was underwhelming. It's a slow win condition with Ensnaring Bridge out, and pretty bad if you do happen to have more than 1 card in your hand.
Sin Prodder is widely played, but I truly dislike it. When it reveals a land or a Chrome Mox, it does nothing, and even when it doesn't, your opponent might let you keep redundant copies of Ensnaring Bridge or Trinisphere to keep you from emptying your hand with Ensnaring Bridge when you don't have enough mana to cast all the extra spells you draw.
Fiery Confluence is another great addition—it's so versatile that it deserves to be a 4-of. It's able to kill creatures, artifacts, planeswalkers, and deal direct damage—it's so good that you will always want 4 copies of this even if it looks overpriced.
The sideboard is quite simple as well.
4 Leyline of the Void is mandatory, since fast graveyard combo decks don't give you time to deploy your hate cards, so you want to put them into play as quickly as possible, even through a Chancellor of Annex.
I see some lists playing Faerie Macabre, though considering that B/R Reanimator plays 4 Thoughtseize and 4 Unmask, I would just stick to Leyline of the Void. It's a dead draw in the late game, but your main concern is only the first few turns.
4 Sulfur Elemental is also necessary since Death & Taxes is a bad matchup. They have plenty of Plains and Aether Vials to get around your Blood Moons, and Flickerwisp to blink Ensnaring Bridge and swing for lethal.
Fiery Confluence is insane in this matchup and is yet another reason to play it.
4 Volcanic Fallout is mainly for Grixis Delver, but also for Elves and any other creatures decks. Every time you board in Volcanic Fallout, remember that you probably want to board out Goblin Rabblemaster.
In my experience, this is a good matchup. There are a lot of factors though, the first of which is the die roll, then how explosive your start is and whether they have a Force of Will for your Blood Moon or Chalice of the Void.
Death & Taxes
As I said, this isn't a good matchup. You have your tools though—multiple Ensnaring Bridges could lock your opponent out of the game, but multiple Sanctum Prelate + Mother of Runes could lock you out of the game as well.
Blood Moon and Magus of the Moon are way better in this matchup than against Show and Tell, where you have plenty of tools, like Ensnaring Bridge versus the Sneak Attack version and Trinisphere versus the OmniTell version.
Moon Stompy is a very simple deck, but also a powerful one—one I suggest you play in Vegas if you're fairly new to Legacy.