Recently, I've been going back to playing in Unlimited. Of course, for Mordecai's sake. I found the current version of Nephthys online, and after making some personal adjustments and optimizations, I decided on the final decklist.
Decklist
With this configuration, I won most of the approximately 20 matches I played. The deck is quite strong and can definitely compete with the top decks. And, of course, it has that fun gameplay!
Possible options:
1. Minus Urdr. It's a matter of taste. Personally, I like this card, and I've always included it in Nephthys decks, at least one copy. In essence, this is the deck where Urdr really shines, rather than just being used to repeat Storm/Ramp. There are many uses – an additional Lich, literally free removal with Lurching, it can single-handedly trade with an evolved enemy follower that another unit would have been killed by. But the best thing is, of course, when it pulls another Mordecai out of nowhere.
However, this card is not essential. What can it be replaced with?
2. Twilight Queen. Like Urdr, it belongs to the category of "win more" cards and performs a similar function. However, unlike it, it is less reliable due to the lack of an immediate effect, and it is also vulnerable to banish. Essentially, the only advantage of this card is the ability to win the Nephthys roulette by drawing two Mordecais, but that's about it... For those who like randomness. Overall, I don't recommend it.
3. Necro Assassin. It used to be in my deck, but now that Curse has become much easier to use, it's fading into the background. The possibility of random removal of ambushes still exists thanks to Lurching, and the body on the board isn't that necessary for this deck. Especially considering that sometimes there is simply no room on the board for it. Nevertheless, it is a worthy option.
4. Third Mordecai. Oh yes, thanks to him, matches are won. However, Nephthys, like other control decks, tends to brick. Even with cheap cards in hand, because there are enough cards that you won't want to play simply because you can. And swapping a 4-drop for an 8-drop... Well, you get the idea, hello Mordecai in the starting hand. And you can't remove anything higher up the curve. So, this is definitely a reasonable option, but you can also do well without it, especially if the deck includes the aforementioned Urdr or Twilight Queen.
5. Skull Ring. This is a bit of a different story. In this particular deck, the card is not very good, although it is suitable, not being a follower for 3 mana. Two skeletons per turn 3 is weak, especially considering that there are no Catacombs or Atomi here, so spamming the board doesn't really pay off. And board space is more valuable. The best outcome is when it revives Unica or Lurching, but there is no particular reason to run the ring otherwise.
6. A little about 2-drops. Other more or less decent options are Soulskewer, Lucky Pig, Lirial, and Spartan Sergeant. But Soulskewer skewers not only enemies but also your shadows, so the chances of an upgraded Death's Breath or Foul Tempest are significantly reduced. You can, of course, hold it, but that's like "saving a card for the whole game and never playing it." And there are enough removals anyway, so it's probably not needed in this deck. I've always considered Lucky Pig to be worse than Unica, both in terms of potential and in the fact that, unlike it, it is not a pseudo-ward. Aggro can easily ignore it, thinking, "Oh, it heals 1 HP," but Unica has to be killed. So, although Lucky Pig is a good option, I don't see any particular reason to run it instead of Unica. Lirial's advantages are well known, but in shadows, Belenus has priority. And the Sergeant is basically just a body on the board, there's not much to say about it. It makes some sense when Soulskewer is included, especially if there is no Moon and Sun, but otherwise, not really.
Cards that I would like to highlight:
1. Moon and Sun. This new legendary is great for Nephthys decks! Universal anti-brick, ping heal/damage, infinite value. The card alone can carry you to the point where you start playing Death's Breath, Khavi, and Nephthys. It gives you twice the number of souls, for both a spell and for destruction, which makes it easier to cast spells with necromancy. A must-have! But no more than two are needed, as you usually play with the same one.
2. Ceres. This is one of the reasons for choosing the 2478 configuration. The card is very strong in itself, with its potential to trade and heal every turn. And healing is needed in a control deck, there should be a lot of it (hello, control Blood!).
3. Spells. With soul conversion, zombie party, and Death's Breath, everything is clear, these are auto-includes x3 without hesitation, as it was before. Foul Tempest is more of a tech card, but in some matchups, it's really impossible without it. Overall, it's a very useful card that shouldn't be forgotten. And Curse – in light of the latest buffs, I tried it in various shadow decks, mainly in rotation, though. But if it's included in a rotation mid-range deck, it's more because it's practically the only cheap target removal there, then here, thanks to the 2-mana cost, the card has become really convenient to use.
That's it. Sorry for the long text, those who are not interested in Nephthys may not read it. And for those who have played and loved this archetype, I hope this will be informative.
And, for fun, here are some of my adventures with bricking Deceive:

This one seems to have been sitting there without removal.

And this one was diligently spellboosting the whole game, you could hear it puffing. In the end, it cast Shift on turn 9, and on the next turn... it put down three golems, lol. Easy game