Phantom Knights (PK) are a powerful combo deck capable of executing large amounts of summons to create a variety of boards. This deck utilizes mostly non-linear combos to produce a consistent end-board. A lot of builds of PK will tend to differ from one another because of the amount of summoning power the deck has; there's a lot of room for customization, and a lot of different types of strategies you can perform with this deck. In this profile, I will outline the approach I use and try to present popular alternatives.
With the summoning power of this deck, it is capable of utilizing a plethora of high Link-Rating monsters that can be used to facilitate OTKs or even to close out rougher games. I will not be going over those in combos, as they will mostly be used situationally at your discretion.
Combos
Normal Summon "Tour Guide From The Underworld" > Trigger Effect > Summon "Graff, Malebranche of the Burning Abyss" > Link Summon "Cherubini, Ebon Angel of the Burning Abyss" > Trigger Graff > Summon "Cir, Malebranche of the Burning Abyss" > Activate Cherubini, send "The Phantom Knights of Ancient Cloak" for cost. Special Summon "The Phantom Knights of Rusty Bardiche" using Cherubini and Cir > Trigger Cir, Special Summon Cherubini.
Tour Guide is just one of the different ways you'll be able to access this board. This setup is very powerful as it grants you access to effectively your whole Phantom Knights engine. This opening play also allows you to misdirect your opponent as to what deck you are playing, which can lead them to make poorly optimized decisions in their attempt to disrupt your turn.
There's many different routes from here to take to get to the end which are all dependent on the rest of your opening hand, but I will continue to go over a very straightforward route given our current game state.
Activate Rusty Bardiche > Send "The Phantom Knights of Torn Scales" to the GY, set "The Phantom Knights of Shade Brigandine" to your field. Activate Ancient Cloak in your GY > Add "The Phantom Knights of Stained Greaves" to your hand. Trigger Torn Scales in your GY > Special Summon it to your field > Trigger Stained Greaves in your hand, Special Summon it to your field, do not increase its level. Activate Torn Scales, discard a card for cost and send "The Phantom Knights' Wing" from your deck to your GY. Xyz Summon "Leviair the Sea Dragon" using Stained Greaves and Torn Scales > Activate Leviair, detaching Torn Scales for cost > Summon Ancient Cloak. Activate PK Wing in your GY > Summon Torn Scales > Xyz Summon "The Phantom Knights of Break Sword" using Torn Scales and Ancient Cloak > Xyz Summon "Number F0: Utopic Future" using Leviair and Break Sword > Special Summon "Number F0: Utopic Draco Future" using Utopic Future as the full material. Activate your set copy of Shade Brigandine, summoning it to your field > Link Summon Union Carrier using Shade Brigandine and Cherubini > Activate Union Carrier, Targetting Rusty Bardiche, Equipping "Dragon Buster Destruction Sword".
This is a very powerful endboard. Provided that your opponent did not disrupt you during certain key moments of your combo, you can easily achieve this end board with pretty much any combination of the cards listed above as well as the different extenders the deck plays. This board gets stronger if you can get an additional PK trap card in your GY. That would allow you to use your Utopic Draco Future to negate by detaching the Break Sword, and during your opponnet's turn you can use the additional PK trap card in your GY to bring back Break Sword to a zone Bardiche points to. This provides an additional point of disruption on your opponent's turn.
Again, this deck is capable of producing this board with pretty much any combination of two level 3 monsters. There's going to be times where you draw in to Stained Greaves or possibly both of your Torn Scales. Using Ancient Cloak to get "The Phantom Knights of Silent Boots" into rotation alleviates a lot of potential bricking alongside the Psychic monsters in "Psychic Wheelder" and "Psychic Tracker", giving you follow-up if your opponent negates your Tour Guide or Torn Scales.
I'll lay out an examples of what your combo might look like provided you do not open with Tour Guide.
Normal Summon Ancient Cloak > Special Summon Psychic by available means > Link Summon Cherubini with Ancient Cloak and the Psychic > Activate Cherubini, sending Graff from your deck > Trigger Graff > Summon Cir > Link Summon Rusty Bardiche using Cir and Cherubini > Trigger Cir > Summon Cherubini from your GY. This combo here will put you right back on track to be able to perform the combos listed above. A similar version of this combo can be performed with Silent Boots and an additional PK in your oppening hand. Additionally, this can also be accomplished with 2 Psychics, 1 Pscycic + 1 E Tele, and any PK with a Psychic.
In these different starting situations, there will be different points through your combo where you have PKs like Silent Boots in your GY which you will be able to banish to add "The Phantom Knights' Fog Blade" from your deck for an extra negate on your opponent's turn with the added benefit of preventing that monster from declaring attacks.
Normal Summon Torn Scales > Activate Torn Scales, discarding for cost > Send Phantom Knights' Wing to the GY. > Special Summon Silent Boots > Link Summon Cherubini with Torn Scales + Boots. Activate Cherubini > Send Graff > Trigger Graff > Summon Cir from deck (note: you do not want to send Graff if you drew into Cir. Instead Special Summon Cir from hand and continue combo as follows) > Link Summon Rusty Bardiche with Cir + Cherubini (note: if you summoned Cir from deck off of Graff, trigger their effect to summon back the Cherubini.) > Bardiche Effect, send Ancient Cloak from deck to GY, set Shade Brigandine from deck. > Ancient Cloak Effect > Add Stained Greaves > Trigger Torn Scales to Special Summon > Trigger Stained Greaves to Special Summon > Xyz Summon Leviair > Activate Leviair detaching Torn Scales to Special Summon Ancient Cloak > Activate PK Wing in GY to Special Summon Torn Scales > Xyz Summon Break Sword using Ancient Cloak and Torn Scales > Xyz Summon Utopic Future using Break Sword + Leviair > Xyz Summon Utopic Draco Future using Utopic Future.
This is another way you're going to be accessing your endboard. With one more piece of extension like an E Tele/Psychic, we'd easily be able to use the set Shade Brigandine to turn into a Link Spider which combined with one of the Psychic monsters can be used to Link into Union Carrier, allowing you to establish your Buster Lock. This line also will put a Silent Boots in your GY which you can activate to get a Fog Blade from deck to give you another piece of disruption for your opponent's turn.
Alterations & Final Thoughts
There are many alternatives to different monsters played in this deck. For example, a popular one is using the Dark Xyz Dragons by summoning them off of the Phantom Knights Rank-Up Magic spell cards. The Xyz Dragons can be very useful to provide you with a quick OTK strategy where you can establish a monster with large ATK and punch in for heavy amounts of damage. You can also choose to forgo the Union Carrier + Dragon Buster setup and utilize something like Predaplant Verte Anaconda + Destroyer Phoenix Enforcer with Artifact Scythe. There's plenty of other alternatives you can play around with, including different extenders like Kagemucha Knight, Junk Forward, or Caligo Claw Crow. Feel free to tinker around and develop your own favored strategy for a more personalized experience. I hope you found this deck interesting and this description useful. Good luck and happy dueling.