My current GDS list. Card explanations below.
The Creatures:
4x Death's Shadow - The namesake card of the deck. Our fetch/shock mana base combined with Thoughtseize and Street Wraith allows us to quickly make Death's Shadow a live threat. It is important to remember that you can pump your Death's Shadow at instant speed by fetching or cycling a Street Wraith, this can turn on ferocious at instant speed as well as surprise your opponents for extra points of damage.
2x Tasigur, the Golden Fang - A 2/2 split on Tasigur and Gurmag Angler is the norm due to Tasigur's legendary status. Tasigur's active can be a powerful source of card advantage and is one mana/delve cheaper but Gurmag's extra power can be the difference in some game. Both enable ferocious and are powerful beaters that can win you games on their own. Tasigur is easier to cast on turn 2 but it is possible with Gurmag if you go T1 fetch seize/IoK, Turn 2 fetch Thought Scour.
4x Snapcaster Mage - Because of our deck's desire to interact early and often with cheap/efficient spells on top of cards like Thought Scour filling the yard, Snapcaster Mage is an automatic 4 of. This card is insanely versatile, letting you cast any spell that is in the yard from the 75 on at most 5 mana. Sometimes casting another hand hate spell on turn 3 can be disruptive enough to give you a massive advantage, or maybe you need to flash back removal, a counter spell, or even a Temur Battle Rage. There are even times it will be correct to Snap-cantrip on your opponents end step, either to Thought Scour and churn out another delve fatty, or Opt and filter/draw a card with a small beater attached.
4x Street Wraith - At times I have dropped down to 3, but I feel convinced now that 4 is correct. It's easy to board out when its bad, and you can slot out less than 4 in situations where you need to bring in more board cards but have nothing else to cut. Cycling at 2 life is the reason we run this card, but hard casting the creature is correct at times. Keep an eye out for opposing swamps, as the swampwalk can let you swing through a stalling board.
Cantrips:
4x Opt - The debate between Opt, Serum Visions or both is one that comes up often, and the answer depends on the deck. Personally, I have found Opt to fit better into our overall game plan, primarily due to it being instant speed. The advantages of this range from allowing us to represent Stubborn Denial in the early turns of the game, either as a bluff or as a non-creature Force Spike for opposing hand hate, land deck spells like Expedition Map in Tron variants and ramp spells in Titanshift, or other sideboard haymakers/things we don't want to resolve such as Chalice of the Void or Blood Moon. Against some decks it is important to start applying pressure early, Opt lets us flash in a Snapcaster on their end step and turn it into card advantage and filtering if need be. While Serum Visions lets you see 3 cards, you don't get to filter the card you draw, which can be to slow in some matchups. Scrying 2 can also pose awkward situations with our fetch heavy mana base, in situations where you want both scrys on top but have to play/crack a fetch on the next turn or cast a Thought Scour. The sorcery speed is also a knock against Serum Visions because your opponents turn can make your scry much worse, while Opt lets you filter and draw at the end of their turn with mana you were able to hold up.
4x Thought Scour - A cantrip that fills the yard goes a long way in a graveyard deck, who knew. Thought Scour enables turn 2 Delve creatures and gives us more targets for Snapcaster Mage. Typically gets worse than Opt by the late game, when the card selection will usually matter more than putting cards in the yard, which fills up quickly anyways with our fetches and interaction.
Hand Hate:
4x Thoughtseize - One of the most powerful cards in the format, snag the card in their hand that is most problematic and gets us closer to casting Death's Shadows. Playing with knowledge of their hand is a huge advantage, allowing you to make more informed decisions when you scry off of Opt, whether or not you can deploy a threat safely, whether or not you need to save removal or use it, and if you can use your Stubborn Denial as a Force Spike to further mess up their game plan.
2x Inquisition of Kozilek - Thoughtseize's 5 and 6, but usually slightly worse except against burn. If you have both a Thoughtseize and IoK in your opener, lead off with the IoK. Practically every deck is casting cheap spells turns 1-3 that advance their game plan or disrupt ours, IoK can take the early play saving the (generally more expensive) payoff card in their hand for Thoughtseize.
Removal: 3x Fatal Push - One of the best removal spells in the format, so why not the full 4? When Fatal Push is good, it's amazing, which is why we have access to the 4th in the sideboard, but there are enough decks out there where this card really bad such as Eldrazi variants, Tron, Grishoalbrand and Titanshift and other removal options are better that running 3 gives us more variance and a chance at removing some of the huge creatures these decks deploy.
1x Lightning Bolt - A lot of times this functions as Fatal Push number 4, as the overlap of what they kill is very broad. Having 1 bolt main gives us a small chance against some of the protection from black creatures that float around in the board, but more importantly we run 1 bolt for the reach of bolt-snap-bolt, which can close out games, especially with the help of K-Commands. I'd be lying if I said I've never used it to pump a trio of Death's Shadows, though this is very fringe.
1x Terminate - Some things are too big for Fatal Push or Lightning Bolt, which is where this comes in. If indestructible creatures are present in your local meta, Dismember might be better. The Phyrexian mana is a cute way to grow your Death's Shadow, but I find that it lines up poorly against decks such as Grishoalbrand and Titanshift, and the time you need it to kill a Goyf and it can't will feel pretty bad.
2x Kolaghan's Command - This card does so much for us. Kills small creatures, kills artifacts, the discard mode can put opponents in a tough bind, and return a creature can range from grabbing a fallen beater, to drawing a card off a Street Wraith, or the value train of looping this with Snapcaster Mage. Never a dead card, Shock + Discard on their draw step is a fine floor for a card.
Ferocious:
3x Stubborn Denial - A card that you want to see pretty much every game, but can rot in your hand in the late game if you're without Ferocious and can be pretty underwhelming as a top deck sometimes. Access to a 4th in the board for any matchup where their non-creature spells matter or you need extra protection for your beaters. Getting comfortable knowing when to use this as a Force Spike goes a long way, as well as knowing when to use it on their game plan advancing cards or holding it to stop removal.
2x Temur Battle Rage - An "Oops, I win" button that can win you games you had no business winnning. Double Strike + Trample is a huge swing on a Death's Shadow or a Delve threat and will usually end the game. Two might be too many in the main board for some metas, because drawing them instead of our creatures or interaction can be rough, but for me it's a nod to the presence of Lingering Souls and other decks capable of blocking for several turns.
Manabase: Running 10 Fetches and 18 lands has felt pretty smooth, especially with 12 cantrips (Opt, Thought Scour, Street Wraith). 15 black and blue sources with 14 red has felt pretty good. One change I would like to make in the near future is -1 Steam Vents + 1 Watery Grave. Black is our most important color, with blue close behind, and having two Steam Vents leads to some unkeepable hands without a black source to cast hand hate, removal or creatures off of. One of each a Swamp and an Island lets us grab either of our most important colors off of Path to Exile or Ghost Quarter, and gives us fetch targets to grab if we fear a Blood Moon.
Sideboard:
2x Ceremonious Rejection - Great for Affinity, Tron, Lantern Control, and Eldrazi as well as some other more fringe artifact strategies floating around.
2x Disdainful Stroke - Bring this in against control, Titanshift, Storm (it hits Gifts Ungiven and Past in Flames through their mana reducers in case you didn't know), Eldrazi, and Tron.
2x Collective Brutality - Amazing against Burn and most aggro decks while also being good against CoCo decks. Bring it in against these decks or against decks that have critical instant/sorceries they are trying to cast, such as Storm where it's good but would be better if it could kill Baral as well as Goblin Electromancer.
2x Rakdos Charm - At least one mode is good in many Modern matchups. Each creature hurting it's controller will punish any opponent casting Lingering Souls or Empty the Warrens (GBx and Storm). Useful against Merfolk for taking out an early Aether Vial or pushing through damage with this and TBR after they cast Master of Waves. Artifact destruction is obviously good against Affinity and Chalice of the Void decks. Instant speed graveyard hate is useful against several combo decks, Dredge, GBx and the mirror.
1x Stubborn Denial - Often gets brought in where your removal doesn't line up well or they cast a lot of problematic non-creature spells, such as removal, Cryptic Command, Scapeshift, Liliana of the Veil/planeswalkers. On the draw against Chalice/Blood Moon decks this usually comes in for an IoK.
1x Fatal Push - When it's good, you want all 4. Simple as that
1x Terminate - There are many things Fatal Push can kill, for everything else, there's Terminate.
1x Izzet Staticaster - Sometimes this is a second Flaying Tendrils, but this is better against Affinity's manlands and Lingering Souls.
1x Flaying Tendrils - Good against Hatebears, go wide strategies, Affinity, Burn, and Zoo/aggro. This over Anger of the Gods because double black is easy for us but double red is not. Both exile, and it is are that I find myself wishing this was Anger when I draw or cast it.
1x Liliana, the Last Hope - Shrinks or kills small creatures, fills the yard while netting you creatures and comes with a powerful ultimate. Great for grinding or weenie removal on a stick.
1x Ashiok, Nightmare Weaver - A filler for Liliana of the Veil. A pet card of mine that has impressed when I have brought it in. Can cause fits in the mirror and against any deck playing efficient creatures or ones that have impacting ETBs or other abilities. Milling out can become a viable win con against some controlling decks. The ultimate is slow, but can be worth using. Something I'll bring in when there's more cards I want to take out for a matchup than I can replace or when I want to attack on a weird angle.
