Skeleton for a Nephthys ritual deck, using a small Fire King engine. The level 8 non-ritual monsters play well with each other and with being destroyed by the small Nephthys non-ritual monsters, EM:P Meowmine is a free level 2 body that also plays well with Spright Sprind. The ratios for Defender of Nephthys, Matriarch of Nephthys & Chronicler of Nephthys are subject to change.
There are so many engines one could splice into a Nephthys deck.
• Fire Kings, but even more. The four level 4 beast-warriors, also Consort Ulkanix & Ponix, and Tenki, Sanctuary & Island. They add power and versatility but take away from the focus on the rituals.
• Spright. Ignoring the cards that lock into level 2 only, one can still splice Blue, Red and Carrot for extension and versatility.
• Simorgh. Bird of Bringing, Onslaught & Repulsion as the searchers and utilities with your payoff bird of choice, like Bird of Ancestry.
• Drytron. To support the ritual spam, with Meteonis Drytron being an excellent choice for summoning the bosses.
• Impcantation. An often-used ritual turbo-support engine, but can be problematic here as the extra deck choices are very helpful.
• Diviner of the Herald with Arc Light & N'tss. Also an easy slot-in for ritual decks, searching the rituals / popping a card and providing fodder and access to synchros.
• True Kings. A small engine with Agnimazud & Diagram for more self destruction, bodies and removal effects, work best along with Fire Kings for more fire targets.
• Windwitches. Same attribute as most of the Nephthys and lead into a free indestructible Crystal Wing.
Alternative individual cards one could include.
• Hand of Nephthys - Old neat card for the original Sacred Phoenix.
• Loud Cloud the Storm Serpent - Additional boss with variable utility.
• Cataclysmic Scorching Sunburner - Free body and burn.
• Windrose the Elemental Lord - Difficult-to-use boss with S/T removal.
• Shinobaron Peacock - Alternative ritual boss with bouncing removal.
• Hop Ear Squadron with Omega - Level 2, synchro access.
• Extra-Foolish Burial - If using the Diviner engine to dump Arc Light.
• Summon Storm - Helps getting the small non-rituals out of the hand and into the field.
• Morganite - In a more pure version, can increase the grind game and monster spam capacity without a drawback.
• Last Hope of Nephthys - It's fine, possibly unnecessary, also completely dead if going first.
• Rekindling - Especially for the extensive Fire King variant, to spam monsters on the field and convert them to extra deck plays.
• Pot of Prosperity - Can afford to lose a few extra deck cards.
• Torrential Tribute - A good trap for more control with the natural drawback of it possibly being turned into a positive here.
• Hraesvelgr, the Desperate Doom Eagle - Neat utility.
• Topologic Bomber Dragon - More explosions.
• Knightmare extra deck package - The usual utility and removal effects.
• Sky Cavalry Centaurea - Battle-based bounce effect.
Haven't tested it.