Xenan Shadow Surge

Xenan Shadow is making the rounds in Expedition, but I haven't seen a posted list, so here's my take on it. I hit Masters today with it, so it feels quite powerful. It punishes control decks successfully, and it feels pretty good against aggro because of all the healing. The deck is fairly linear, but there are a few choices that might seem strange.
First off, the deck is centered around Shadow Surge and pushing Shadow influence. The main build around combo is Karvet, Redeemed and Severin of the Dark. However, even if your Severin gets hit with Turn to Seed the deck has plenty of finishing power, so stick with it. Katra, The First Seal is a really powerful card when she gets going, so that can be difficult to deal with, and then Acantha Ascending has the big Shadow payoff that will basically end the game if your opponent does not have removal at that point. However, don't be afraid to play Acantha early to get a 4/3 flier that generates bodies. It can activate Devour and push extra damage that will set up your market lethals with At Any Cost or Silverblade Menace. Other than that it just has the solid Shadow removal cards, and Petition to get closer to your win conditions. Also, don't forget that Trail Maker also generates immediate surge, so you may want to Katra + Trail Maker in some spots and hold up Severin for a turn or 2.
Finally, I teched in Marionette Cross and Eremot, Mindsplinter because I don't like running 4 Marionettes since playing 2 is already really asking for trouble, and Eremot is so strong that you can often draw out an early Turn to Seed and free your Severin to get to work.
I've seen several people playing Wasteland Broker in this deck, but I think that is a really bad option because you are not a control deck, and you don't have a strong draw engine. You want to be playing threats and backfooting control decks, not trying to outvalue them. Icaria, First Reaper is a really strong card, but I found 1 in the market to be sufficient as you don't want to get too top heavy.