Nocturne Nightfall Combo w/ Deck Guide

Overview:

Level up Diana and Nocturne as fast as you can and us Diana and other Nightfall units trade down the board until you reach T7 or T8, where you kill your opponent with a Nocturn + fearsome combo. Use Gems and Fading Memories to trigger nightfall, and save Shroud of Darkness for your combo turn with Nocturne so that you don't lose to board clear/removal. Use Diana + Zenith blade for an alternate win-con.

Mulligan:

Always mulligan for Lunari Duskbringer or Stygian Onlooker (only if you're attacking T1)—the deck is full of cheap units so don't be afraid to mulligan away your entire opening hand. Lunari Duskbringer is really great for enabling and flipping Diana faster, whereas attacking with Stygian Onlooker on T1 is great for levelling your Nocturne faster, even if you don't get the Nightfall effect.

Playstyle:

If you're attacking T1, play your Stygian Onlooker and try to get an attack with it. It's usually okay to let it attack into a 1/1 or 1/2 unit, but in some matchups, you might prefer to look for a more valuable trade. For the entire first part of the game, your goal is to attack with your nightfall units as much as possible in order to level up your Nocturne. Your goal during this part of the game is to make sure your opponent doesn't build-up a threatening board. Use Tyari the Traveler and Mentor of the Stones to buff your units (especially Diana) and create favourable trades. Don't block with your Nightfall units so that you can use them to attack more and level up your Nocturne. Crescent Guardian should always be attacking to deal chip damage and force blocks. You don't need to have dominance over the board like a midrange deck—as long as you force trades and keep the enemy's board relatively unthreatening, you don't need your units to stay alive (although it would be nice, obviously). You do want to keep Diana alive though, as she can be an alternate win-con with Zenith Blade in case you don't draw Nocturne.

During the early stages of the game, you should also be hoarding as many 1-cost and 2-cost units as possible, especially Stygian Onlooker. Play only enough of them to level your Diana and Nocturne quickly. You also want to be looking for Nocturne, using Pale Cascade and Stalking Shadows for some extra draw.

On T7 or T8, whichever turn you're attacking on, you want to play Shroud of Darkness > Nocturne > 2 or 3 units. Your board should look something like this: 7-attack Nocturne w/ Spellshield, 4-attack Stygian Onlooker, 2-attack Lunari Shadestalker, 2-attack Lunari Duskbringer, etc., and also whatever units that were still alive on your board before this turn. You should be able to win the game off of this attack.

There is also a chance that you can just kill your opponent really quickly by generating a huge elusive unit with Mentor of the Stones + Pale Cascade + Lunari Shadestalker. Use Bastion to protect her from removal—and sometimes you want to precommit the Bastion before your opponent even plays a spell, to stop them from using Frostbite or Silence on it.

Other Card Explanations:

Fading Memories is a great Nightfall trigger, and you can use it on Stygian Onlooker (to stock up on cheap units to play with Nocturne) or Lunari Duskbringer for more Nightfall triggers.

Lunari Duskbringer on T1 can enable a T2 Diana with nightfall trigger, which can be a really powerful tempo swing. Great on Lunari Shadestalker as well.

Mentor of the Stones can give you gems, which you can use to keep units healthy and also trigger Nightfall. Using his support buff on Diana is also puts your opponent into a very scary situation, where they have to somehow deal with a 4/4 Quick Attack/Challenger. It's also nice to have a 4/5 elusive Lunari Shadestalker.

Pale Cascade is just a really broken card, works really well on Diana, Shadestalker, and Crescent Guardian.

Tyari the Traveler helps your units live and get more attacks in.

Crescent Guardian does chip damage and the threat of 5 damage kind of forces your opponent to block, sometimes unfavourably. T1 Duskbringer > T2 Tyari > T3 Duskpetal Dust > T3 Crescent Guardian > Support Attack will give you a 5/5 Overwhelm on T3. Pretty good right?

Unspeakable Horror prevents you from running out of cards, and overall just a better Vile Feast in this case. Pulling a Stygian Onlooker is great for your finisher, Doombeast is a solid card, and even if you pull a Duskrider off of this, it's not that bad due to the sheer amount of Nightfall triggers that this deck has.

Stalking shadows is similar to Fading Memories in this deck: if you draw a Stygian Onlooker off of it, it's two more cheap units to combo with Nocturne. Currently it's a 1-of, and I'm hesitant in running it as any more than 2, as it can't draw you into Nocturne. If drawing Nocturne is inconsistent, you could just run a 3rd Nocturne.

Zenith Blade is best used on Diana to give her extra survivability and the potential to end the game if you drop a lot of nightfall units in a turn for buffs to her attack.

Grasp, Withering, and Ruination for sustain and removal. These cards are meta-dependant, and given the strength of the Daybreak package, I'm thinking Midrange decks will probably be very strong, so a few Ruinations can help you survive T6 or T7 when the deck begins to fall behind Midrange decks. There is also Guiding Touch for sustain and draw, if you find that removal is not necessary.

Thanks for reading this guide, I think this deck will be pretty good.