While Dominaria was a very exciting set overall and will for sure bring new cards to almost all, if not every format, one card in particular stood out to me as soon as I saw it; Board the Weatherlight screamed out to me. As an avid Lantern Control player in Modern, I know how absurd Ancient Stirrings can be. Along with being one of the key pieces that makes Lantern tick, it’s also a huge reason Gx Tron variants have remained dominant for so long. With that in mind, I immediately began to brew decks that could potentially abuse it. From my testing, I found that the card works great in Marvel, Saheeli Superfriends, and an old Standard boogeyman: GW Tokens.
The first deck that I wanted to work on was Saheeli Superfriends. It has performed excellently in all testing we did, but at the end of the day, it just wasn't my style. The deck is full of synergy - the only cards that Board the Weatherlight does not grab in the mainboard are Satyr Wayfinder, Felidar Guardian, Abrade, and Dig Through Time - but being able to dig deeper to help find that exact card you need to stabilize is exactly what this deck wants to be doing. While it does include a Turn Four infinite combo, it's much more of an overwhelming value-based deck, rather than the glass-cannon combo deck that it seems to be at first glance.
The cards that Board the Weatherlight does not grab are pivotal to the deck. Satyr Wayfinder fills the graveyard for Ishkanah, Grafwidow and Dig Through Time, as well as helps meet the deck’s mana requirements, which every Four-Color deck can use some help with, and is also relevant as an early blocker against aggro decks. Abrade is a catch-all removal spell for those aggressive decks, as well as removal that is relevant in the already hard Marvel matchup, and against Smuggler's Copter decks. Dig Through Time just helps the deck find more must-answer threats or the final pieces needed to assemble the combo, and piece together a win.
The other new cards in the deck are Shalai, Voice of Plenty and Urza's Ruinous Blast. Obviously, Urza's Ruinous Blast is worse overall than Fumigate, but being able to dig deeper to find a board wipe through Board the Weatherlight has proven to be quite invaluable thus far. Shalai does a great job of protecting your walkers from spot removal including Vraska's Contempt and any damage-based removal spells. She also allows you to have protection to go for the combo kill without fear of it being interrupted by any form of removal-based disruption.
The deck that I have really liked so far in testing though, is GW Tokens. Much like its Standard counterpart, the deck's goal is to simply protect its must-answer threats which will quickly end the game when left unchecked. While Archangel Avacyn had good synergy in the Standard deck, I feel she often doesn't bring enough to the table in Frontier. Lyra Dawnbringer, on the other hand, is the epitome of a must-answer threat. She can easily stonewall most of the threats in the format, even including Hazoret the Fervent after a single pump effects or +1/+1 counter from the many anthems in the deck such as Dromoka's Command; Shalai, Voice of Plenty; Nissa, Voice of Zendikar; as well as a Gideon, Ally of Zendikar emblem. Yet again, Shalai does a great job of protecting the Planeswalkers, and also benefits from getting buffed by Lyra for incidentally being an Angel. Her ability to buff your team in a board stall while still being able to fly over and poke for damage in a midrange mirror is great. With Lyra and Shalai, red-based aggro decks pretty much can no longer win, as their removal is ineffective and the angels can gain back as much as the red deck's attacks.
If it wasn't already apparent by the decks I tend to play, I think Gideon, Ally of Zendikar is the best card in the format. Historically, this was one of the best Gideon decks in past Standard. GW Tokens does a great job of protecting him, and maximizing the value he can provide. He and Nissa both get immediate value when they hit the board, and protect themselves. The deck also does a pretty good job of protecting your life total against red-based decks, and all of the walkers can easily start closing out the game once you’ve stabilized. Walking Ballista does a great job at picking off little creatures, as well as insulating the removal-light deck from the dreaded Saheeli-Felidar Guardian combo kill. I think most players will be hard-pressed to find another deck that generates this much value.