Two (or more, in this case usually elemental) artifacts, each of which is a counterpart of the other. Typically they are either identical but distinguished by their users and names, or Yin and Yang-like different.

One common plot element is {{the Hero}} having to acquire an ArtifactOfHope to allow him to defend against and/or defeat the villain, who has the ArtifactOfDoom, making each item a NemesisWeapon to the other. It's also common to distribute them among siblings, partners or a group of TrueCompanions.

There may be a SetBonus by having all of them. They may also benefit from LikeCannotCutLike.

They might be in some way morally aligned; in this case, they're the object equivalent of GoodCounterpart[=/=]EvilCounterpart.

If each piece of a set of corresponding objects is elementally attuned, each of their wielders will usually have PersonalityPowers corresponding with the object's element.

Compare HolyHandGrenade and UnholyNuke, which are (usually) two spells that oppose like this.
See also UnstoppableForceMeetsImmovableObject, EmpathicWeapon and EvilWeapon. Often combined with StockWeaponNames. OnlyTheChosenMayWield is also common. Often ColourCodedForYourConvenience.

JustForFun/NotToBeConfusedWith JustForFun/SwordCounterpart[=/=]JustForFun/GunCounterpart.

Sometimes you GottaCatchThemAll to enter a place or learn a special technique; compare AllYourPowersCombined, DismantledMacGuffin, and SignatureDevice.
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!!Examples:
[[foldercontrol]]

[[folder:Anime & Manga]]
* ''Manga/InuYasha''. The title character bears the sword Tessaiga which can kill 100 demons/yokai at a time. His brother Sesshomaru uses the sword Tenseiga, which can't harm living beings (but can kill underworld creatures) and can bring creatures back to life. Each sword was created from one of the fangs of their demon father.
%% * ''Anime/TransformersArmada'': the Star Saber, Skyboom Shield, and Requiem Blaster.
* ''Anime/YuGiOhTheMoviePyramidOfLight'' has the villain Anubis wielding the Pyramid of Light, the eighth Millennium Item created in the image of Yami Yugi's Millennium Puzzle and as such appears as an inverted white version of it.
[[/folder]]

[[folder:Comic Books]]
* ''ComicBook/TheLegendOfTheChaosGod'' is a Disney multi-'verse crossover comic centering on an ancient monster kept imprisoned after it was [[SealedEvilInACan sealed into]] [[CrystalPrison a ruby crystal with a gold setting]]. As long as the crystal and setting remained separate, the monster couldn't escape. But someone stole the two and wanted to revive it. The consciousness in the crystal influenced characters as it tried to get itself reunited with the setting.
* ''Franchise/WonderWoman'': The Lasso of Truth and the Lasso of Submission. [[ComicBook/WonderGirl Cassie]]'s Lightning Lasso is made to call the other two to mind but doesn't really fit as it's designed to channel Zeus' powers through her.
[[/folder]]

[[folder:Films -- Live-Action]]
* In ''Film/TheMummyTrilogy'' the black Book of the Dead awakens Imhotep and grants him immortality, while the gold Book of Amun-Ra makes him vulnerable.
* The Franchise/MarvelCinematicUniverse introduced the Darkhold in its serial television installments, an ArtifactOfDoom that grants knowledge of whatever the reader wants but inevitably corrupts them into obsessively and immorally achieving their goals. ''Film/DoctorStrangeInTheMultiverseOfMadness'' makes it the central driver of conflict, but also introduces the Book of Vishanti, an ArtifactOfHope that provides knowledge of whatever the reader [[WantsVersusNeeds needs]] to overcome their enemies.
[[/folder]]

[[folder:Literature]]
* In ''Literature/ConstanceVerityDestroysTheUniverse'', it's revealed that The Great Engine was designed as a counter to The Key, having been built to inhibit its entropy-accelerating effects on existence itself.
* In the second ''Literature/{{Dinotopia}}'' book, 'The World Beneath', Arthur searches for the other half of an old key that opens a door in the World Beneath. Its owner, Oriana, ends up going with him on the expedition.
* Creator/MichaelMoorcock's ''[[Literature/TheElricSaga Elric of Melnibone]]'' stories. The twin swords Stormbringer and Mournblade, one possessed by Elric and the other by Elric's cousin (and enemy) Yyrkoon.
* ''Literature/HarryPotter'': The wands of Harry and Voldemort are rare in that they both contain a feather from the same phoenix and react when used against each other.
* Maybe parodied in ''Literature/JourneyToTheWest'': After stealing the dreaded Crinsom Gourd (capable of sucking inside and melting people called by name in front of it) and putting a fake in its place, Monkey challenges the owner Silver Horned King to a duel, claiming that he possess the "male" counterpart of his gourd. He does an identical trick later, this time claiming that he possessed the "female" counterparts of a trio of deadly bells.
%% * Each set of rings in ''Literature/TheLordOfTheRings'', except for the supreme (and evil) One Ring, which has no counterparts.
* In Creator/DavidEddings' ''Literature/{{Malloreon}}'' series, it turns out that the Orb of Aldur has an evil counterpart, the Sardion.
* ''Literature/ANightInTheLonesomeOctober'' features a counterpart pair of magic wands: one is empowered to open a gateway for {{Eldritch Abomination}}s to enter the world, and the other to hold the gateway closed in opposition to the first.
* The Choeden Kal from ''Literature/TheWheelOfTime'': two incredibly powerful {{Amplifier Artifact}}s, one each for the male and female halves of the One Power.
[[/folder]]

[[folder:Live-Action TV]]
* ''Series/{{Angel}}'' had an episode involving the title character needing to find the parts of a key that would open a portal and allow him to find a young man being held prisoner in another dimension. He was being pressured into via Cordelia being tormented by a Wolfram and Hart guy who'd hacked her visions.
* ''Series/TheLordOfTheRingsTheRingsOfPower'': Initially, Sauron wanted to create two rings of power for himself and Galadriel, but Galadriel learns just in time about true identity, causing him to flee. Celebrimbor still creates three Rings of Power for the Elven kind, at Galadriel's request: Vilya, Nenya, and Narya.
%% * ''Franchise/PowerRangers'' morphing devices.
[[/folder]]

[[folder:Tabletop Games]]
* ''TabletopGame/DungeonsAndDragons'':
** ''TabletopGame/DungeonsAndDragons'' starting at least with AD&D 1.0 quickly became ''full'' of these, thanks to the signed alignment system; good/evil equivalents of artifacts and spells just suggest themselves. For example, the Regalia of Might: It has Good, Neutral and Evil sets -- each including a crown, orb and scepter.
** A non-alignment based example would be elemental summoning items: bowl commanding water elementals, brazier commanding fire elementals, censer controlling air elementals, stone controlling earth elemental.
** Modules [=UK2=] ''The Sentinel'' and [=UK3=] ''The Gauntlet''. The Gauntlet was a magic item designed to destroy the Keep of Adlerweg. The Sentinel was created to oppose and eventually destroy the Gauntlet.
* The Mightstone and Weakstone from ''TabletopGame/MagicTheGathering'' (and its associated novels) are two halves of a Thran powerstone that was used to open a portal to Phyrexia on Dominaria. They later became Urza's eyes when his planeswalker spark ignited.
[[/folder]]

[[folder:Toys]]
* ''Toys/{{BIONICLE}}'': the Mask of Light and the Mask of Shadows. They were combined once in TheMovie.
[[/folder]]

[[folder:Video Games]]
* ''VideoGame/DragonAgeOrigins'' had the twin rings Dusk and Dawn, while the expansion had Dumat's Spine and Dumat's Claw, a sword and a dagger created from the bones of the first Archdemon.
* ''VideoGame/{{Egoboo}}'': The Sporks of Yore. They serve as a DismantledMacGuffin, and each of them is attuned to a different virtue.
* Seraphim, the sword of ''VideoGame/ExitFate'' protagonist Daniel Vinyard, and its counterpart Cherubim.
%%* ''VisualNovel/FateStayNight'' has Archer's Chinese swords, Kanshou and Bakuya, that have a yin-yang theme going on and magnetically attract each other.
* ''Franchise/FinalFantasy'': A recurring theme related to the series's themes of DarkIsNotEvil and balance between light and darkness is that the four Elemental Crystals have counterpart Dark Crystals. They pop up in ''[[Videogame/FinalFantasyI I]]'', ''[[Videogame/FinalFantasyIII III]]'', and ''[[Videogame/FinalFantasyIV IV]]''. ''[[Videogame/FinalFantasyV V]]'' has no Dark Crystals, but does have a counterpart quartet of Crystals in the second world.
** The Ultima Weapons from ''VideoGame/FinalFantasyVI'' are mentioned to be this, even though only one of them is a piece of equipment (namely a sword), while the other one is a monster.
** In ''Videogame/FinalFantasyVII'', Sephiroth seeks the Black Materia that can call Meteor. Aerith in turn has the White Materia that can call Holy, which can destroy Meteor.
** ''VideoGame/FinalFantasyXII'' has the Dawn Shard, Dusk Shard, and Midlight Shard, three pieces of Nethicite originally wielded by the Dynast-King, Raithwall. All three shards were carved from a much larger crystal, the Sun-Cryst. Much of the early plot is centered on trying to find one or more of them while keeping them out of the hands of TheEmpire. They are both powerful political/historical symbols, signifying being the heir to the Dynast-King, and potent magic weapons in the hands of the Empire's MadScientist.
*** A more straightforward example from the same game is the sword the Dynast-King used to carve the shards off the Sun-Cryst and the ''new'' sword given the Ashe by the local PowersThatBe to signify her as his successor. The older sword could be used to destroy the Sun-Cryst (freeing Humanity from the Gods' tyranny), while the newer one could be used to harvest shards of divine Nethicite in order to forge an empire of her own (and take revenge on those who killed her family and enslaved her kingdom). When the party goes in search of the Sun-Cryst, even ''she'' isn't sure which one she intends to use when they find it...
** In ''VideoGame/FinalFantasyTacticsAdvance'', there's the Ayuvuir Red and Ayuvuir Blue, originally dual-wielded by the Hero Gaol.
* ''VideoGame/FireEmblemRadiantDawn'' has the two blessed swords formerly wielded by the heroine Altina, the golden Ragnell and the silver Alondite.
* ''VideoGame/Ghostbusters1990'' for the UsefulNotes/SegaGenesis, along with a tablet the group [[DismantledMacGuffin assembles]] during the game, has the "Eye of the Flame," a red jewel that, when placed in the assembled tablet, opens a deep hole that's a portal to the World of Evil. The "Storm's Calm" is a blue jewel held by the final boss that closes the portal when placed in the tablet.
* * ''Franchise/KingdomHearts'' has a million and one Keyblades, and with several Keyblade wielders, it's no surprise that this trope is pulled every so often.
%% ** Sora and Riku: in the first game, Riku gets an [[DepartmentOfRedundancyDepartment evil keyblade of evil]] to unlock peoples' hearts rather than, more harmlessly, doors.
** Sora and Mickey: both have the standard 'Kingdom Key' weapon, except Mickey's is gold. It shows they're one and the same, but Mickey is higher-status.
* ''VideoGame/KingdomOfLoathing'' has a set of five elemental clubs for the Seal Clubber, which are smithed from a [[http://kol.coldfront.net/thekolwiki/index.php/Bad-ass_club Bad-ass club]] and an item obtained from an Infernal Seal, and a high-tier chefstaff for each element, all of which are made of a staff associated with the respective elements and elemental feathers, noodle dishes, mushroom wine and wads.
* ''VideoGame/KingdomsOfCamelot'' on Facebook has four elemental Guardians: Wood, Ore, Stone and Water, each of which raises production of that resource (water actually raises Food, there is no 'water' resource) and adds to attack or defense stats in battle. SetBonus applies here.
* ''Franchise/TheLegendOfZelda'':
** ''VideoGame/TheLegendOfZeldaI'': The iconic Triforce is portrayed in this game as this, with Zelda having the Triforce of Wisdom and Ganon the Triforce of Power. It wasn't until the second game that the Triforce of Courage was introduced (and, starting from that game's ending, associated permanently with Link).
** ''VideoGame/TheLegendOfZeldaSkywardSword'': The Goddess/Master Sword and the Demon King's sword, [[spoiler: Ghirahim]]. Also, among the collectibles you can find are Amber Relics (pretty much anywhere); their counterpart, the Dusk Relics, can also be found pretty much anywhere but only during the Silent Realm trials.
* ''VideoGame/MightAndMagic VIII'' has Elsenrail and Glomenthal. Though they have no story influence, their flavour texts describe them as linked yet opposite, with Elsenrail being the Blade of Light and Glomenthal being the Blade of Dark, and the forging of these Swords of Balance having destroyed the Forge of Chaos.
* These pop up a lot in the ''Franchise/{{Pokemon}}'' games, usually tied to legendary Pokémon in some way.
** Ho-oh and Lugia, mascots of ''VideoGame/PokemonGoldAndSilver'' and their remakes, get not one but two sets. The Rainbow Wing and Silver Wing are their respective feathers, while the Clear Bell and Tidal Bell are simply associated with them; both sets can be used to summon the respective birds.
** Groudon and Kyogre, mascots of ''VideoGame/PokemonRubyAndSapphire'' and their remakes, get the Red Orb and Blue Orb, which are used to control the two titans in some way. Normally, the Red Orb is linked to Groudon while the Blue Orb is tied to Kyogre, but the anime switched it around for some reason. As of ''Omega Ruby'' and ''Alpha Sapphire'', the Orbs also allow Groudon and Kyogre to undergo [[SuperMode Primal Reversion]]. ''Heart Gold'' and ''Soul Silver'' added a third Jade Orb for Rayquaza, but it hasn't been seen since.
** Dialga and Palkia, mascots of ''VideoGame/PokemonDiamondAndPearl'', get the Adamant Orb and Lustrous Orb respectively, which boost their same-type attack bonus when held. ''Platinum'' adds a third counterpart, the Griseous Orb, for its mascot Giratina, which has the additional effect of transforming Giratina into its Origin Forme.
** Arceus, special snowflake that it is, gets an entire set to itself: the 16 (later 17) Plates, each of which represents a different elemental type. While any Pokémon can hold a Plate to boost the power of moves of the respective type, Arceus can use them to change its own type and the type of its signature move, Judgment.
** Reshiram and Zekrom, mascots of ''VideoGame/PokemonBlackAndWhite'', get the Light Stone and Dark Stone; unlike most of the other ''Pokémon'' examples, these ones actually are the legendaries in question, being the remnants of the dragons' bodies after their clash in the backstory. Interestingly, fans have discovered a third counterpart called the God Stone in the games' code, but it was apparently DummiedOut; the common assumption is that it would have been linked to Kyurem or the original dragon.
** Genesect gets a set of four Drives, special cassettes that change the type of its signature move Techno Blast when held, as part of its upgrade by Team Plasma.
** Solgaleo and Lunala, mascots of ''VideoGame/PokemonSunAndMoon'', get the Sun Flute and Moon Flute, which were created to offer prayers to the aforementioned legendaries and can be used to summon them. Interestingly enough, both flutes must be used together to have any effect; it's the location that determines which of the two legendaries gets invoked.
** Silvally was an attempt to recreate Arceus and its power, so it's no surprise that it got its own equivalent of the Plates, special disks called Memories, which alter its type and the type of its signature move Multi-Attack.
%% * The White Chronicle and the Black Chronicle in ''VideoGame/RadiantHistoria''.
* The ''Videogame/SoulSeries'' has Soul Edge and Soul Calibur which represent chaos and order (Calibur was made from a purified shard of Edge, so it's still kind of evil). Both get stronger when Soul Edge absorbs souls.
* ''Videogame/{{Suikoden}}'':
%% ** The Bright Shield and Dark Sword runes in ''Videogame/SuikodenII''.
** ''Videogame/SuikodenV'' has the Dawn and Twilight runes; they're opposites to each other, but not opposed, as they both work to keep the Sun rune in check.
* The Atlantean Scion from the original ''VideoGame/TombRaiderI''. Three pieces, one for each ruler of Atlantis.
* ''VideoGame/{{Wild ARMs 3}}'' has a pair of gemstones that act as counterparts with one another. Unfortunately, they react like matter and antimatter when they come in contact with each other.
[[/folder]]

[[folder:Western Animation]]
* In ''WesternAnimation/{{Blackstar}}'', the Powersword and the Starsword were created by a fission of the Powerstar. Johnny Blackstar wields the Starsword against the Overlord, who covets it.
* In Filmation's re-imagining of the ''Blackstar'' concept, ''WesternAnimation/HeManAndTheMastersOfTheUniverse1983'', He-Man and Skeletor originally each wielded half of the Power Sword. This concept shows up in the earliest toy and comic releases, but was scrapped by the time the first episodes were in production.
* ''WesternAnimation/TheMask'': Brother Mask and Sister Mask, which can control the Mask's powers. [[spoiler: Tragically, the legend of these Sibling Masks was Dr. Pretorius' fabrication. Sister Mask DOES allow ''him'' to control Stanley with a remote control. Naturally, [[BewareTheNiceOnes Stanley is decidedly not happy]] when he finds out.]]
* ''Creator/RankinBassProductions'':
** In the 1980s version of ''WesternAnimation/{{ThunderCats|1985}}'', the Sword of Omens had an evil counterpart in the Sword of Plundarr.
** The relationship is inverted in the [[WesternAnimation/ThunderCats2011 reboot series]]: the Sword of Omens was created as a ''good'' counterpart to the Sword of Plundarr, forged from the metal slag that was left over after its creation.
* In ''WesternAnimation/XiaolinShowdown'', many Shen Gong Wu have sister Wu that are used in conjecture in order to utilize their abilities more effectively. The most notable ones are the Yin-Yang Yo-Yos, either of which allow their user to enter the Yin-Yang world, but both are needed in order for the user to come back out with their chi whole, otherwise a good user will become evil and vice-versa.
[[/folder]]
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