This version tries to be more efficient at clearing difficult creatures like Hullbreacher, Spirit of the Labyrinth and planeswalkers like Narset, Parter of Veils and Teferi, Time Raveler. The inclusion of Lightning Bolt and Terminus helps with these permanents. I play no more than 2 Day's Undoing because usually after the first one resolves you don't need another. In addition, it is exclusively a combo card that pairs with a Narset, Parter of Veils or Hullbreacher and doesn't play to the board. I also decided to cut the Mountain for another Volcanic Island to support the mainboard Lightning Bolts better. I updated the fetch lands accordingly.
For sideboard I am trying to stick a floodgate and back it up. Cards like Energy Flux, Torpor Orb, Containment Priest, and Blood Moon are all very strong against the top decks. I decided to opt for Blood Moon over Back to Basics to hedge against Pyroblast, and Urza's Saga while also bolstering my mainboard red sinks. I do not want to lose to combo decks so I am siding both 3 Surgical Extraction and 2 Flusterstorm to pair with the 3 Snapcaster Mage's in the main deck.
Pairings
Snapcaster Mage | Lightning Bolt
Snapcaster Mage | Surgical Extraction
Jace, the Mind Sculptor | Terminus
Day's Undoing | Narset, Parter of Veils
Blood Moon | 2 Volcanic Island
Sideboard Guide
Reanimator (7)
-3 Prismatic Ending
-2 Lightning Bolt
-2 Terminus
+3 Surgical Extraction
+2 Flusterstorm
+2 Containment Priest
Notes
Prismatic Ending kills Containment Priest so holding it to play around sorcery speed removal is often more correct.
UR Delver (6)
-2 Jace, The Mind Sculptor
-1 Force of Negation
-2 Force of Will
-2 Days Undoing
+3 Pyroblast
+2 Flusterstorm
+2 Blood Moon
Mirror (6)
-2 Terminus
-3 Swords to Plowshares
-1 Prismatic Ending
+2 Flusterstorm
+3 Pyroblast
+1 Mystic Sanctuary
Notes
Post Board we leave all of our counter magic because there are so many important spells that swing the game very quickly. In general its better to be patient rather than jamming the combo. One trick is to let opponents hullbreachers resolve and then when they days undoing you can fight over the hullbreacher with removal like blasts and plows. The advantage of this is they have to fight over the days because letting it resolve draws me a fresh 7 and I get to be the first to act. Second it means they are trading permission for cards that have no business being good in the matchup like plows.
4C Control (8)
-2 Force of Negation
-4 Swords to Plowshares
-2 Terminus
+2 Back to Basics
+2 Flusterstorm
+3 Pyroblast
+1 Mystic Sanctuary
Lands
-2 Hullbreacher
+1 Back to Basics
+1 Blood Moon
Death and Taxes (4)
+2 Containment Priest
+1 Mystic Sanctuary
+1 Torpor Orb
-2 Hullbreacher
-2 Force of Negation
Hogaak
-1 Jace, the Mind Sculptor
-2 Prismatic Ending
-2 Lightning Bolt
+3 Surgical Extraction
+2 Containment Priest
Doomsday (9)
-3 Prismatic Ending
-4 Swords to Plowshares
-2 Terminus
+3 Surgical Extraction
+1 Torpor Orb
+3 Pyroblast
+2 Flusterstorm
