Based off of a list from Corbin Hosler and many people on MTG Goldfish.
The Combo
The centerpiece of the list is Soulflayer. Basically you want to fill your yard with big creatures (i.e. Zetalpa) using Grisly Salvage, Gather the Pack, and Grim Flayer, then delve those creatures with Soulflayer to create a creature with pretty much every keyword ability known to man, and smash the next couple of turns for the victory.
Initial Thoughts
From watching the video, the deck doesn't really have any interaction with combo decks (aside from Thoughtseize) and it seems to be a bit slower (which could be because I'm used to Modern, which is significantly faster than Pioneer), so I wanted to brew a bit and see if I could make it faster/more consistent. That being said, I thought the deck idea was awesome and wanted to try and put another spin on it. All of this below are ideas that I've had. I haven't tested this out and I'm really looking to get feedback on my ideas and use this as a forum to share ideas with each other.
Ideas I had/Changes I made
I made a number of changes to the deck. First, I went with Grim Flayer over the usual Lotleth Troll. As much as I love Lotleth Troll, it's not fantastic in multiples and mainly serves to discard creatures from your hand. I wanted to try out Grim Flayer because he Surveil 3's each time he hits, which can really help fill your 'yard and fix your draws.
I also wanted to put in Traverse the Ulvenwald because, from watching the videos, it seemed like there were a few times when Corbin really wanted to draw Soulflayer, Zetalpa, or another "piece of Exodia," as he put it, but couldn't off of his draws or digging spells. Traverse circumvents that, but both it and Grim Flayer are best with Delirium. This shouldn't be that hard with a self-mill deck, but I'd like to make that easier by adding artifacts and sac lands. There really only is one good land that sacrifices itself, and that's Fabled Passage. For cheap artifacts that sacrifice themselves, there are a few options, but I went with Renegade Map as it helps fix your mana and is kinda like 4 extra lands, making it a little easier to run only 18 lands (I could be completely off on this, please let me know). There are a bunch of other solid cheap artifacts like Soul-Guide Lantern and Tormod's Crypt which are good against all the Underworld Breach decks that I'm even considering running mainboard.
I also mentioned that the deck didn't really have any interaction, so I put in 4 Thoughtseize. Also, since we no longer have Lotleth Troll, we don't have any discard outlets. To circumvent this, I added in two Collective Brutality and two Radical Idea, the former is just a great utility card against a number of decks and the latter helps us dig through our deck even faster and can be cast from our graveyard, so it doesn't matter if we mill it! I went with Radical Idea over Chemister's Insight as it's cheaper, but it may be better to just draw more cards. I also went with three Striped Riverwinder purely because it has hexproof and it cycles, allowing us to rip through our deck even faster. Playing blue also allows us to play Treasure Cruise and/or Dig Through Time, but I couldn't figure out what to cut to make room for them. In addition to the myriad abilities that Zetalpa has, I also added in Banehound to give Soulflayer both haste and lifelink.
Am I crazy for cutting...
Some notable omissions: I decided to cut Questing Beast, Murderous Rider, Nullhide Ferox, Rhonas the Indomitable, and Rankle, Master of Pranks. I did this mostly because I'm on a budget (all of them, but mostly Beast & Rider) and others I wasn't too hyped on (Ferox, Rhonas, Rankle). For those that have experience with this archetype, how important is it for Soulflayer to have deathtouch? how frequently does the deck win with Soulflayer vs. beatdown with Rhonas, Ferox, Beast? how important is Rider/Swift End? how good is Rankle vs. the field? Please let me know which of these cards really makes the deck work!
Closing Thoughts
As for some closing thoughts and questions to incite discussion: I think Tamiyo, Collector of Tales could potentially be really good in this deck, but I'm not convinced she's fast enough - is she worth it? Given that the curve of this deck is so low, should I still include Sylvan Caryatid? Red also has a number of good draw/discard/Jump-start spells (plus Dreadbore, Bedevil, and Kolaghan's Command), so we could just as easily make this deck Jund instead of Sultai. Thanks everyone for making it this far and I really appreciate your ideas!
