Archfiend Regenesis

This is based on my new latest pet deck for locals, Ritual Pendulum Archfiends! The meta of Advanced Format won't allow them to be much more than Rogue playable; but in Domain, their toolboxing and consistency contribute to some truly heinous turn 1 or turn 10 plays.

The new Archfiend support really ties everything together, but Fiendsmith is the main consistency and grind engine of the deck. Tour Guide is the strongest Normal Summon in the deck, and gets the whole deck rolling if uninterrupted.

The Game Plan

The deck is focused on smothering the opponents in card advantage;

then using recursive interruptions like A Bao, Abomination, Rage, Luce, Sage, BLS, and the suite of highly searchable Archfiend Traps to simultaneously control the board and gain more advantage by triggering GY effects;

then shuffling everything back with Mutiny, Sequence, and Skull Archfiend to do it all again the next turn.

For example: [normal summon Tour Guide > summon Buio > Xyz into Melomelody > Link into Requiem > add Mutiny in the Sky] is a 1-card combo that can turn into Fiendsmith Sequence + Necroquip + Aerial Eater on the field, with Tract in hand + the Necroquip draw + whatever GY effect you trigger off Aerial Eater's send.

You can do a lot with just that. Add Doom Regina off Tract and Usurpation by sending Heiress for full gas; add Lurrie and Highness, then banish Tract to make Lacrima; or just add Regina and Emperor and Pendulum Summon the rest of your hand.

Archetypes

Regenesis is here because, although most any Archfiend offers great domains for the deck, I needed the extra domain to play Sage for the OPT negate. Also, Regenesis Archfiend's summoning condition plays well with all the 2500 ATK monsters, so I figured that adding more of the archetype would give a better chance of opening with the required monster. On top of that, Regenesis also has a very good grind with powerful disruptions and beatdown.

Unchained here is the key to a few strategies. For generic GY recursion, Yama revives almost anything, and Rage/Anguish add back any Fiend that has found its way to the GY. The other reason is to trigger effects like Pandemonium and Tricorn or to clear zones or get key cards in the GY. If you have an unused Archfiend Usurpation and a way to summon Yama > Rage, you can set Ghastly Glitch to pop Rage and search/summon whatever Fiend you send. Bonus points if you also have Tricorn in hand.

The Ritual of Light and Darkness... I love this Archetype. Despite BLS not being DARK. Fortunately, that works in our favor here since Regenesis Archfiend is also EARTH. In non-singleton versions of this deck, I prefer to just run 2 Skull Archfiend of Chaos for the unmatched utility of recycling ANY cards from GY/banishment and the perfect compliment to Preparation of Rites. Even if Skull Archfiend gets banished, Archfiend Emperor can bring it back once he is in the EMZ. However. I needed another on-theme card to recycle for Skull Archfiend, the Spell/Traps are actually quite good interaction, Gurifoh is a Fiend, and BLS is EARTH. So here we are. Using almost any Fiendsmith combo, you can arrive at the Usurpation > Ghastly Glitch + Soul of Rage combo described above to send + add Gurifoh to get consistent turn 1 access to Mind Shuffle.

Archfiend Usurpation is probably my favorite Archfiend card. The toolbox utility of setting/resetting any Archfiend Trap is exceptional; which is the main reason for running Labrynth and Vivid Tail. Berserk Archfiend is a questionable choice, but works well in combination with Unchained, and like all Archfiend cards, is now highly searchable. The ATK gain isn't negligible either. Darkbishop is another questionable pick. I almost never summon it. That may change soon since Protective Stone Gardenscaping can set That's Six! which drastically improves both Darkbishop and Masterking.

Labrynth's purpose here is twofold: 1) more consistent and varied ways to bounce Doom Regina to add back Usurpation, and 2) Trap toolbxing and recursion. Arias the Butler is just a great card, and his 2500 DEF stat is perfect for our Deck Master. Lady Lab's effect to tutor Normal Traps from the deck is an enormous boon. The standard combos set up plenty of interaction for 1 or 2 turns, but being able to tutor a Trap OPT helps ensure you are never out of interaction. This makes Jar of Avarice especially playable, which is the final piece in the endless cycle of fiends...

What Else

That's the most of it. The main problem I am having with building Archfiends is space. There are definitely a few sub-optimal picks.

Luce and A Bao might seem like easy flex spots but they are both strong interuptions, are important for grind game, and make great boss monsters, especially under Archfiend Strategy. A Bao is truly the main boss of the deck on the other players' turns, but if all goes well, they will have plenty of Traps and other big Fiends to take their minds off her until it's too late.

Unchained Abomination is the most likely suspect for switching out, as its destruction effects will likely make few friends at the Domain table (though not necessarily). Muckraker from the Underworld is a good option for extending, protecting the board, and triggering Heiress from hand, so it might take the spot. Wave High King Caesar is not as overwhelmingly powerful in Domain (2 negates vs 3 opponents), but could be as frustrating as Unchained Abomination. Masterking is a strong possibility as it totally changes the grind game of the deck, but requires some building around. 

I would also like to add a couple more Fiend pendulums like Archfiend Eccentrick, Hallohallo, and Gallugallud the Endless Enigma to better enable worthwhile pendulum summoning. Gallugallud is a decent Advanced Ritual Art target for Matador and scale 9 is excellent.

I would wholeheartedly love to include Resonators and RDA in the deck, but the Extra Deck is simply too tight and too vital to fit enough pay-offs for dealing with the Synchro locks attached to them. Bone Archfiend, however, is a very useful card, and a Synchro-focused variant is very possible. There are also a couple decent options for Chaos Archfiend's float effect, and Chaos Angel is always a great card.

This list is a work in progress, so it and this primer will be updated as I experiment and discover better techs and strategies for Domain. Archfiends are incredibly flexible if you can manage to avoid the locks on Royal and Highness, so once you are familiar with the lines, trying swapping some stuff out until it suits your taste. The Archfiend/Fiendsmith core can lean hard into Fusions and Links, generate a large amount of levels and bodies for Rituals or Synchros, or even facilitate Tribute summoning since many combos don't even require the Normal Summon. Although not as generically, Rank 3, 4, 6, 7, and 8 monsters are also valid Extra Deck targets; depending on how you build. Enjoy!