In the early days of Modern there were Life from the Loam decks, typically Jund, that used the powerful card to simply grind opponents into dust. Failing that, they tried to ride a Seismic Assault to victory. This list seems very similar to those decks, with the important addition of Jace, Vryn’s Prodigy.
Jace lets this deck dig for Life from the Loam, dredge Loam back more often, loot away excess copies of Seismic Assault and Flame Jab, and take some of the pressure off you while you set up your engine. It’s an ideal card for this kind of deck, to the surprise of approximately no one. The other blue cards in the list are nice and all, with Serum Visions and Gitaxian Probe to help you dig and Electrolyze and Izzet Charm as flexible pieces of interaction, but the new splash here is really for Jace.
However, that’s not the only interesting aspect to this list. Tarmogoyf and Young Pyromancer give the deck an aggressive package that makes it much better-rounded. The creature base thus looks more akin to a Delver strategy than something slow and grindy like Loam, but the beaters do good work here. Pyromancer is great with Retrace, letting you turn all your excess lands into both damage and creatures, and the power of Seismic Assault is maximized when it can close out games quickly by targeting your opponent rather than just containing their battlefield until they run out of resources.
Tarmogoyf and Pyromancer are powerful enough to stand on their own, so they do not dilute the deck by much, and adding a new angle of attack is invaluable, especially against the myriad fast combo decks that exist in Modern. Without the discard offered by black, this deck has little to no disruption against fast combo in game 1, so the aggressive elements give you a chance until you can bring in your sideboard cards, mostly counterspells in this list. As you can see, there is a healthy suite of counters in the sideboard with two copies of Swan Song and the full four Negates.
The rest of the sideboard is fairly generic, although I do like Threads of Disloyalty a lot in a post-Twin format, since the stock of Abrupt Decay has gone down considerably. Red can have trouble dealing with bigger creatures like Tarmogoyf, so Threads is a great option. In fact, I would like to see a Dismember in the maindeck for that reason, especially in a deck that sees so many cards between Loam and Jace. Perhaps the Worm Harvest can be trimmed, since that card seems much too slow for Modern, but it could be an important piece for gaining inevitability in slow matchups.
The mana base is solid and surprisingly conservative. The only utility lands are a single Raging Ravine and a single Ghost Quarter, so I have to applaud the discipline. I might look for space for a second creature-land, but I’d make sure it is red, since Seismic Assault and Flame Jab are so color-intensive. For that reason I like both filter lands in this list, since the basics are necessary against more aggressive decks to preserve your life total, and having a Forest on the battlefield and drawing a Seismic Assault can be embarrassing,
Because of Loam I may want to add a ninth fetchland to the deck, which makes Sulfur Falls look expendable, but I could also see cutting the third Steam Vents, since it is easy to play too many shocklands.
Jace has made its impact in Modern already by appearing as a key piece of Grixis Control, so it’s not surprising to see it show up in other places, but this is such an ideal home for the card and I am such a big fan of Life from the Loam that I am excited to see if this deck can become a Modern mainstay.