There are a lot of things going on in this build, and there’s a lot of tension as well. The goal is to take advantage of a bunch of different synergies while still making sure to not be run over early by a creature rush or be too exposed to Saheeli Rai.
The key question this deck seeks to answer is how do we maximize the value of Liliana, Death’s Majesty while keeping ourselves alive and in reasonable shape, and having a decent deck when she doesn’t show up?
I tried several builds, but none of them seemed impressive until I combined her with Nahiri, the Harbinger. Nahiri into Liliana is a very impressive 4-5 punch. You usually will get to discard twice. If you have access to Linvala, the Preserver or Emeria Shepherd you can bring one back, but also effective is to use Archfiend of Ifnir. In that case, the first discard puts it into the graveyard (if you didn’t have time to cycle it), and the second one activates the Archfiend of Ifnir you bring back.
Nahiri, the Harbinger also answers the question of what you are going to do when you flood on mana, since the deck needs to play a lot of mana sources and often cycles several spells early.
This makes Corrupted Grafstone happen. In order to use Corrupted Grafstone properly, you need to be sure there will be a card in a graveyard. Having 1-mana cyclers does that for you, supplemented by Shock and Archfiend of Ifnir. It can still occasionally be an issue, but usually it works out. The key turn is often when you hit 5 rather than 4 mana, depending on your draw, so there should time to cast a removal spell or cycle an Archfiend of Ifnir to turn on the Corrupted Grafstone. Archfield of Ifnir also has the advantage in that it can turn the Corrupted Grafstone black without paying black mana, which can be important.
With full sets of two key planeswalkers, Oath of Liliana becomes impressive, as does Oath of Chandra, and this in turn makes me even more excited to play Gideon, Ally of Zendikar, along with the prospect of playing him on turn 3. I’d want a second copy, but the deck has many demands on its slots, and I couldn’t find the space.
If Gideon, Ally of Zendikar is banned, that isn’t a big deal and you can substitute Gideon of the Trials or Gisela, the Broken Blade in that slot, or perhaps if things are not too fast you can turn it into a fifth big creature.
Chandra, Torch of Defiance would be great if the mana worked for that, but we are pushing it in that department as it is. Double-red is not going to happen without a serious mana overhaul, but there is a chance that it is worth it especially if Gideon, Ally of Zendikar goes down. Using her to accelerate out your high end seems promising.
Emeria Shepherd means you want access to a lot of Plains, as does Linvala, the Preserver, as does the need to cycle on turn 1 for your best starts. You have a comfortable amount of white mana here, so a little compromise is possible, but not a ton. It seems clear that Emeria Shepherd is the best high-end reanimation target to make sure you win long games, with Linvala, the Preserver being the best for staying alive and stabilizing the board. It’s possible you’d want to be able to choose which one you are most interested in, but those slots are in high demand. If you decide not to use Emeria Shepherd, the deck can move away from Evolving Wilds, but I am not convinced that this improves matters.
The sideboard needs to have a way to get rid of your red removal spells, which means you need to put in at least 6 cards, and you don’t want to rely on creature or artifact removal being good there. For now, that means Archangel Avacyn, Transgress the Mind, and Anguished Unmaking. That seems like a reasonable general response to such things, leaving you with a deck full of threats. There is a decent chance that true control decks are well positioned against you and this isn’t especially fixable, but this gives you a fighting chance without selling out your board.
Transgress the Mind seems like the right approach against Saheeli Rai as well. You need to tap out to play your game—give or take Shock mana—so you want to break up the combo and see how much fear you need to show, then play your cards to outclass theirs and likely wipe the board with Archfiend of Ifnir. While he’s in play, you are safe if you hold any cycling card, and later you can hold up Cast Out.
There are a bunch of people suggesting aggressive decks that go wide. This is why you have access to Fumigate, along with the ability to buy time with Fatal Push. If this is a serious portion of the opposition, you can also add a 3rd copy of Linvala, the Preserver and otherwise ramp up your defenses. Given historical experience, if you combine enough cheap removal with good planeswalkers and sweepers at the high end, nothing those decks could contain seems that dangerous, and Cast Out is on hand to handle Gods. There are certainly builds that threaten to run you over despite that.
This deck does have a rather bad Glorybringer problem. Both Archfiend of Ifnir and Emeria Shepherd have exactly 4 toughness, so it’s easy for Glorybringer to ruin your whole day by killing both your guy and your planeswalker, and there might be a lot of them out there. The only reasonable solution I can think of would be Lightning Axe, which can kill Glorybringer before it can attack, and for which holding up mana is reasonable. I don’t want to be the guy who throws Lightning Axe in every deck, and it otherwise shouldn’t really be here, but it might prove necessary for this reason. If that happens, don’t forget that paying 6 mana is an option later in the game!