This deck seeks to improve the control and midrange matchups by slowing down a turn compared to normal Grixis Death's Shadow.
Instead of deploying a threat on turn 2, this deck holds up counterspell or removal, and cantrips/tutors with secrets if interaction isn't needed. By waiting until turn 3, we can rely more on our fetches to turn on Shadow, instead of losing tempo by casting Thoughtseize. K-command on wraith, or deprive bouncing a shock can also help turn on shadow.
Given UW control's improved ability to deal with Tron lands, and Assassin's Trophy helping against Tron for BG/X, I think we are likely to see a more midrange/control centric meta. This makes delve threats and discard spells that much less effective, as remove and card advantage are abundant.
By sacrificing some speed and removing delve threats, we can up the land count and open up the late game k-command/snapcaster engine. With Mausoleum Secrets, we can maintain our threat count while opening up the ability to tutor shadow, push, or even k-command in the late game. Vendilion Clique also does some work against terminus and planeswalkers.
The main only plays Death's Shadow at sorcery speed. By focusing on an instant speed strategy, we can keep the tempo and hopefully prevent our opponent's game-winning threats from ever resolving, rather then try to make up for the value they are getting when they resolve a planeswalker, etc.
In playtesting, this feels more like a delver deck than a GDS deck, where instead of dealing 3 damage a turn starting turn 2, we deal 4-10 damage a turn starting turn 4.
