Updated for current standard Core 2020!

Abzan Midrange dudes, the deck, with over the top combo finisher with Bolas's Citadel. I got the basis of this deck from Frank Karsten's article and this decklist.

To explain, the deck outside of Bolas's Citadel provides virtual card advantage in the explore package, various utility cards such as Knight of Autumn and Basilica Bell-Haunt, a threatening top end with God-Eternal Oketra and Doom Whisperer, and survivability with all the incidental life gain. 

With Bolas's Citadel out, Doom Whisperer and the explore creatures allow you to churn through land pockets and gain life when Wildgrowth Walker is out, Verdant Sun's Avatar allows you to almost carelessly drop your deck into play, and Sammut being a one of can allow you to mush your deck onto your opponent as a secondary alternative to sacrificing your board to a citadel for only 10 life when you could be attacking for damage much beyond lethal. As of Core 2020, I recently added Scheming Symmetry to the 60 to allow the deck to pay 1 life to put missing combo pieces on the top of the library, while also being able to use it as a vampiric tutor against decks that we have little to fear about them tutoring for an answer to this deck.

The sideboard aims to shore up to what is being played in my meta. Much of which should be self-explanatory in why it was included to account for planeswalker decks, white weenie, mono-red, and reclamation decks. Outside of the decks mentioned, most of the other decks in the format have overlapping answers to the decks that were already mentioned. The only card I've had to explain why it was included was Gaea's Blessing. I added it over an additional Duress and Cry of the Carnarium is to allow me to recycle cards in my graveyard that were removed and allow me to shuffle my deck if I hit a land pocket with a Bolas's Citadel active. As of Core 2020, I added 3 copies of Veil of Summer. It handles blue and black based decks quite when to allow the deck to protect it's threats and combo.


The Sideboard Guide™  is mostly copy-pasted from the TappedOut decklist link this deck is mainly contrived from. I wanted to explain the general strategy and reasoning for the cards you're bringing in and taking out (updated matchup profiles, (under construction this weekend for strategy and reasoning).

ESPER CONTROL/ HERO/ MIDRANGE/ SUPERFRIENDS
-3 Gift of Paradise
-4 Knight of Autumn
-2 Merfolk Branchwalker
-1 Bolas's Citadel
-1 Scheming Symmetry

+3 Duress
+2 Vraska's Contempt
+1 Immortal Sun
+3 Veil of Summer
+2 Gaea's Blessing

MONO-RED
-3 Bolas's Citadel
-1 Verdant Sun's Avatar
-1 Samut, Tyrant Smasher
-1 Scheming Symmetry

+2 Cry of the Carnarium
+2 Vraska's Contempt
+2 Mortify

WHITE WEENIE
-1 Bolas's Citadel
-1 Verdant Sun's Avatar
-3 Gift of Paradise
-1 Samut, Tyrant Smasher

+2 Cry of the Carnarium
+2 Vraska's Contempt
+2 Mortify

WILDERNESS RECLAMATION/ RAMP DECKS
-3 Gift of Paradise
-1 Basilica Bell-Haunt
-1 Merfolk Branchwalker
-1 Wildgrowth Walker
-1 Jadelight Ranger

+3 Duress
+2 Mortify
+2 Gaea's Blessing
+3 Veil of Summer

RAKDOS MIDRANGE
-2 Bolas's Citadel
-1 Verdant Sun's Avatar
-3 Gift of Paradise
-1 Merfolk Branchwalker

+2 Mortify
+2 Vraska's Contempt
+1 The Immortal Sun
+2 Veil of Summer

ARISTOCRATS
-1 Bolas's Citadel
-1 Verdant Sun's Avatar
-3 Gift of Paradise

+2 Vraska's Contempt
+2 Cry of the Carnarium
+2 Mortify

GRUUL MIDRANGE
-1 Bolas's Citadel
-1 Verdant Sun's Avatar
-3 Gift of Paradise

+1 The Immortal Sun
+2 Vraska's Contempt
+2 Mortify

GATES
-4 Basilica Bell-Haunt

+2 Vraska's Contempt
+2 Mortify

SIMIC FLASH
-3 Gift of Paradise
-2 Scheming Symmetry
-4 Knight Of Autumn
-1 Verdant Sun's Avatar
-1 Merfolk Branchwalker
-1 Bolas's Citadel

+3 Veil of Summer
+3 Duress
+2 Cry of the Carnarium
+2 Vraska's Contemp
+2 Mortify

ORZHOV VAMPIRES
-3 Gift of Paradise
-4 Knight of Autumn
-2 Scheming Symmetry

+2 Cry of the Carnarium
+3 Veil of Summer
+2 Mortify
+2 Vraska's Contempt

TEMUER ELEMENTALS
-2 or 3 Knight of Autumn (dependant on if they are running Mass Manipulation or not)
-3 Gift of Autumn
-2 Scheming Symmetry

+2 Cry of the Carnarium
+2 Vraska's Contempt
+2 Mortify
+1-2 Veil of Summer (dependant on if they are running Mass Manipulation or not)

BOROS MENTOR
-1 Bolas's Citadel
-1 Verdant Sun's Avatar
-3 Gift of Paradise
-1 Samut, Tyrant Smasher
-1 Merfolk Branchwalker

+2 Vraska's Contempt
+2 Mortify
+3 Duress