**Edit 1**

After a lot of playing, I made my first set of revisions:

• Archfiend of Ifnir -3: Archfiend was a good tool for cycling and clearing out wide boards, but he often felt like a way to cycle rather than a creature, often clogging my hand until I could find a good turn to play him, and then I would still need to have actual discard effects, as cards like Liliana do not actually count as discards.
• Champion of Wits -3: Champion was a powerful tool for drawing and clearing the board with Archfiend, but often I found that I didn't want to discard the cards in my hand just to draw more, especially in aggro and midrange matchups, so I cut them for more pure draw.
• Chart a Course -4, Glimmer of Genius +3: Similar to Champion, this card is powerful for cycling and empowering Archfiend, but it was disadvantageous that I could only play it on my turn, most importantly during the early game where I would need to save mana for counterspells.  Glimmer of Genius was a great replacement because, although it costs more, I could strategically play it on my opponent's turn and get through more of my deck with the scry effect it has.
• Golden Demise -1, Yahenni's Expertise +1: Golden Demise is really strong, but I wanted an even more powerful board clear that I wouldn't need a creature for to set up (looking at you again, Archfiend). The -3/-3 effect obviously clears more creatures, and allows me to play a midgame Supreme Will or Search for Azcanta for free.
• Vraska's Contempt +2: An easy addition, I was having trouble with midrange creatures that could slip through the cracks of my counterspells, especially god cards like Hazoret that would just start plowing through my life total.
• Supreme Will -2, Disallow +4, Syncopate +2: Supreme Will was great for grabbing the handful of minions out of my deck in the later stages of games, but became worse as a counterspell effect as my opponents amassed greater numbers of lands. Syncopate and Disallow gave me more ways to consistently react to my opponent's plays, giving me more time to draw out my deck that I lost from removing a couple copies of Supreme Will.  In addition, Disallow's ability to proc on pretty much any effect makes it useful to deal with tricky enchantments and creature abilities.
• Omniscience +1: Fun card I thought I'd throw in that ended up being pretty useful in control matchups.  With your wincon combo being pretty mana-intensive and all-in, playing this during an earlier turn makes it considerably easier to get your combo pieces up while waving away their answers to it. Also makes it easier to manually search for a Nexus of Fate, as you won't have to worry about having enough mana to play it after using your draw and search effects.

**End Edit 1**

Still trying to refine the decklist, but the basic gameplan is:

• Play your cards that draw when you don't think you'll need to counter something.  When you have to discard, you're trying to discard Razaketh.  Nexus of Fate is another good discard as it will pop back into deck.  You can even discard a Liliana if you have an Eldest Reborn up as you can just revive it.  Feel free to cycle your Archfiends if you don't need them on board (i.e. if you really need the draw from the cycling instead), otherwise try to get them on board, as their aoe effect is really powerful with the draw power of the deck.
• You're trying to get Liliana and Razaketh on board at the same time, ideally with a Nexus in hand, so use your revival effects to make that happen.  The optimal revive is Eldest Reborn reviving Liliana, because then Liliana can revive Razaketh and you've played him and Liliana for free.
• If you have a Nexus in hand, play it. If you don't and have another creature on board, activate Razaketh's effect to search it.  If you can't do either of these, you've used your combo too early, but try to use your draw and good luck to find it.
• Every turn, attack with Razaketh and generate a zombie token with Liliana.  This will allow you to sacrifice a creature for his search effect if you don't draw either Nexus.  Don't mind the discard of that Liliana effect; again, Nexus of Fate can't actually be discarded due to its secondary effect and it will pop back into the deck. Take those extra turns like this until you win.

And there it is.  Again, the decklist is unrefined: I would probably put in another Razaketh, I just haven't been able to test that as I am a poor man atm with no wildcards to spare :).  If you're looking for other creatures to include, Apocalypse Demon worked really well when this was a Liliana's Contract deck, as the large amount of cards you're playing/discarding make it huge, and you can generate zombie tokens to keep it untapped.  I didn't include it in the maybeboard for the reason that the intent is for this to be a combo centered around Razaketh and it just didn't have a place.  I'd also like to test other removal spells, like Moment of Craving or Vraska's contempt, since the deck is lacking life gain and Fatal Push doesn't catch every minion.

Finally, obviously the combo of this deck is susceptible to removal (in fact I currently have no way to deal with cards like Cast Out), so my suggestion is to play it by ear.  Wait for your opponent to have a big mana turn so you can pop off, or bait removal with your other creatures and spells.  Your opponent can't untap their lands if you Nexus and they never get another untap step.  Since Razaketh has flying and is a huge creature at 8/8, it's likely that you'll either go through combats unchecked, or at most have to spend a couple turns burning life to get through 1 or 2 opposing flying creatures. Always remember that you have revival effects to bring back the combo if it gets countered or destroyed.