So Travis Woo Brewed this one up a while back and i decided to make some changes to it. the basic idea of the deck is to put your life total incredibly low, some times even into to the negatives, and kill your opponent with Death's Shadow. Here's a quick run-down of the list;
Angel's Grace and Phyrexian Unlife: these cards allow you to continue to play the game even if you have a negative life total. Unlife is good because it's an enchantment with a lasting effect, and Grace is good because it has split second.
Spoils of the Vault and Ad Nauseam: these cards allow you to go from 20 life to the negatives very fast while finding you whatever combo piece you're missing.
Thoughtseize and Read the Bones: Discard to help against grindcore and combo match-ups that also helps to protect the combo. Bones helps keep the blood flowing and both lower our life total
Simian Spirit Guide and Pentad Prism: best fast mana in Modern allows you to go off when completely tapped out.
Fling: helps against decks that put out blockers so you can't just attack in with Shadow.
Lightning Storm: the original Ad Nauseam kill card, we bring this in against control decks so we can kill them at instant speed, also helps if they Slaughter Games our Shadows.
And finally, Death's Shadow: the kingpin of the deck, Shadow is our only real creature. having built the deck around this guy, he is a monster that can easily murder our opponents out right if they don't respect him.
Sideboard;
Leyline of Sanctity: while our deck is pretty resilient against remove and counterspells, discard can be a major problem. I suggest bringing this four in against Jund, Rock, Burn, and Storm.
Drown in Sorrow: We may want to lose life, but we want to do it on our own accord. Bring a couple of these in against Tokens, Podless, Elves, and Delver.
Wear / Tear: Deal with any pesky permanents. bring in against Affinity, Storm, Boggles, and Twin.
Silence: I really don't want to deal with counterspells, but i also don't like when my opponents combo me out. bring these in against Goryo's Breach, Storm, Twin, and Ad Nauseam
Slaughter Games: Just because we're a combo deck, doesn't mean we like other combo decks, so we get rid of their win cons. Sometimes I'd even bring this in to get rid of hatebears like Thalia, Guardian of Thraben or Ethersworn Canonist. bring in agisnt Ad Nauseam, Twin, Storm, and Podless.
