"Ghostrick" is a portmanteau of the words "ghost" and "trick"
All of the non-Xyz Monsters introduced thus far have a common effect: "Cannot be Normal Summoned, unless you control a "Ghostrick" monster. Once per turn: You can change this card to face-down Defense Position".
Also, the Xyz Monsters, except for "Ghostrick Socuteboss" and "Ghostrick Angel of Mischief", share the following common effect: "If this card is sent to the Graveyard: You can target 1 other "Ghostrick" card in your Graveyard; add that target to your hand".
"Ghostricks" are either Level (or Rank) 1 Fiend, 2 Spellcaster, or 3 Zombie-Type Monsters, with one Xyz Monster corresponding to each Level combination, except for "Ghostrick Angel of Mischief".
They feature a variety of effects, mostly revolving around flipping monsters face-down (both yours and your opponent's) and protecting themselves as long as they are face-down. The three strata of monsters each follow a set of general effect guidelines:
The Level 1 monsters react to destruction or attacks, providing bonuses and acting like hand traps; they share a prankster, infantile appearance, maybe hinting to the "tricks" they play against the attacks of the opponent's monsters;
The Level 2 monsters have effects related to Battle Position control, allowing you to search for a monster or stall your opponent's moves; they share a feminine appearance.
The Level 3 monsters all provide useful bonuses while they are face-up or when flipped face-up. Their effects range from searching to burning, or even milling your opponent's deck or giving bulk to a "Ghostrick" monster; their motif is basically of male figures of Halloween and Folklore.
Most of the Ghostrick monsters aren't strong by themselves (the normal-summonable monsters cap at 1600 ATK, thus they're left relying heavily on getting "Ghostrick Mansion" (which can be searched with "Ghostrick Stein") on the board as soon as possible in order to launch several consecutive direct attacks early in the game. Since "Mansion" also protects any face-down monsters from attacks, it is easy to repeatedly activate Ghostrick monster's effects like "Ghostrick Jiangshi" and "Ghostrick Witch". "Ghostrick Scare" and "Swords of Concealing Light" are also useful in this deck to provide disruptions and lockdown, respectively. "Swords of Concealing Light" also serves as good set-up for direct attacks when paired with "Ghostrick Mansion" and allows you to take down strong monsters with "Ghostrick Alucard". "Ghostrick Specter" and "Ghostrick Lantern" add more defenses to this deck, and are most valuable when the "Mansion" isn't available.
Even without Field Spells, this deck has interesting deck thinning capabilities. "Ghostrick Skeleton" can be used to banish up to 5 cards face down from your opponent's Deck, and if your opponent allows you to repeat this each turn can devastate. Since the cards are face down, even Decks that benefit from banished cards, such as Chaos or "Tyranno Infinity" Dinosaurs, cannot gain their banished monsters effect or count them to the total banished monsters.
Arguably, the best beater of the deck is "Ghostrick Ghoul", which works much like "Blackwing - Sirocco the Dawn," albeit only lasting for one turn. The Xyz monsters "Ghostrick Dullahan" and "Ghostrick Alucard" also provide nice, easy to summon beaters that support the other members with powerful and aggressive effects. Also, these two recover a "Ghostrick" card from the Graveyard when destroyed, to help maintain Card Advantage. In addition, "Ghostrick Socuteboss" provides excellent support by destroying a monster once per turn whose ATK is lower than the combined ATK of all "Ghostricks" in play — and rendering its vacant card zone unusable. Combined with "Ghoul", this can make for lasting board wipe, though it may take time to be effective.
The deck has useful, albeit limited swarming capabilities as well, with "Ghostrick Mummy" allowing extra summons, "Ghostrick Doll" providing decent monster search (plus battle position rotation), and "Ghostrick Mary," which can summon any "Ghostrick" in the deck whenever you take damage. In spite of all this, the deck does best with outside swarm options reinforcing the Xyz monsters ("Tour Guide From the Underworld" to quickly Summon "Alucard", "Kinka-Byo" for "Dullahan" etc).
Some non-"Ghostrick" cards that may help the Deck include "Grave of the Super Ancient Organism", "Dark Armed Dragon" and "Pot of Dichotomy". The first is capable of completely shut down Decks that have powerful Nomi/Semi-Nomi monsters as key cards, such as "Stardust Dragon", "Judgment Dragon", "Black Luster Soldier - Envoy of the Beginning", "Gishki Zielgigas" etc, while keeping the "Ghostrick" Deck itself untouched. The second one can give this Deck more muscle and Field-wiping capabilities, making it so the deck doesn't depend only on "Ghostrick Ghoul" to have a beater; however, it will be useless if used in conjunction with "Grave of the Super Ancient Organism". "Pot of Dichotomy" can recycle "Ghostrick" monsters and skipping the Battle Phase is not a very huge problem, since the Deck relies most on setting the monsters and using their trigger effects, activated upon their Flip Summon. "Gozen Match" can be used to Stall even more and "Masked Chameleon" can give the Deck more flexibility, allowing you to perform Synchro Summons, by Summoning "Ghostrick Specter" or "Ghostrick Mummy".
Most of Ghostrick monsters are Zombies, so it's possible to use support for it in this Deck. "Skull Conductor" can be used to summon "Mummy" + "Des Lacooda" or "Jiangshi" / "Plaguespreader" / "Painter" + "Stein" / "Bone Crusher" for a Xyz or Synchro Summon.
This Deck focus on milling your opponent's Deck and win by Deck out. "Ghostrick Parade" is the only recommended Field because of its searching effect and damage to your opponent is unecessary. Note that sending cards to your opponent's Graveyard may help their strategy, so "Ghostrick Skeleton" and "Masked HERO Dark Law" are used to banish the cards instead.
Other cards which prevent battle position changes, whether of the "Ghostrick" player's monsters or the opponent's, such as "Gaap the Divine Soldier" and "Gravity Axe - Grarl" can halt most, though often not all, of the "Ghostrick" player's moves. In addition, a monster Summoned by "Raging Cloudian" will be nearly impossible for the "Ghostrick" player to get rid of.
"Goblin Fan" is a continuous trap that can destroy any monster card that is Level 2 or below the second it's Flip-summoned. This includes about 2/3 of the Ghostrick monsters, and since many of them rely on their Flip effects, rather than raw power, this one trap card can be devastating to any Ghostrick user's strategy.
The "Ghostrick" monster's battle-flipping effects resemble the activities of children pranksters or mischievous spirits: popping out and scaring people, then running away and hiding. This is underscored by the archetype name "Ghostrick" a blatant portmanteau of the words "ghost" and "trick".
The "Ghostrick" archetype was originally released in Shadow Specters, which debuted in the U.S. in November 2013, and may have been intended to coincide with the celebration of Halloween. The "Ghostrick" monsters are largely based on mythological creatures that children in the western world would dress up as for Halloween (witch, ghost, Jack-O'-Lantern, Frankenstein's Monster, Mummy, etc.), and their playstyle (as described above) mirrors the tradition of trick-or-treating.
"Ghostrick" monsters' artworks share the background scheme with the "Lightsworn"s, as they have the same concept of patterning.