"Sky Scout", originally known as "Harpie's Brother", is not a Harpie card because it does not have 「ハーピィ」 in its Japanese name. It was renamed to clarify this.
When "Harpies" were released (some of the first monsters released that would later become an official archetype), they didn't have much support. From Rise of Destiny onward, however, "Harpies" became more balanced and powerful with occasional support cards released. Structure Deck: Lord of the Storm has aided this archetype with cards such as "Hysteric Party" and "Harpie's Pet Baby Dragon", while also featuring a lot of other Harpie-related cards in it. Afterwards, "Harpie Queen" was released in Force of the Breaker, providing ways to search "Harpie's Hunting Ground".
With the release of Lord of the Tachyon Galaxy, Harpies get some tremendous boost, while also solidifies the deck's focus of maintaining advantage and Xyz Summoning. "Harpie Channeler" is essentially the main card in all Harpie-based decks, as she can Special Summon another Harpie monster from the Deck while also assists Xyz Summoning of Rank 4 or 7, while "Hysteric Sign" helps searching either "Elegant Egotist" or any Harpie cards you may need, depending on how you use it. The Xyz Monster in this archetype, "Harpie's Pet Phantasmal Dragon" can protect your other Harpie monsters from attacks or targeting effects, along with direct-attacking ability as well.
Legendary Collection 4: Joey's World also provides more support for this archetype (while also reprinting important Harpie-related cards as well). "Harpie Dancer"'s effect can be utilized for reaping more benefits from "Harpie's Hunting Ground", or providing more swarming capabilities when coupled with "Divine Wind of Mist Valley". They also have their ultimate Spell Card, "Harpie Lady Phoenix Formation", which can decimate your opponent's field of monsters, but disallows you to Special Summoning monsters from your Deck, Extra Deck and skipping your Battle Phase, making it a double-edged sword with hefty drawbacks.
"Harpie Lady 1", "Harpie Lady 2", "Harpie Lady 3" and "Cyber Harpie Lady" have the name condition "(This card's name is always treated as "Harpie Lady".)". Since they all have their name treated as "Harpie Lady" everywhere, including while in the player's Deck, a player can only have a total of 3 of any of these cards and/or the Normal Monster "Harpie Lady" in their Main Deck and their Side Deck combined (for example, 1 "Harpie Lady", 1 "Cyber Harpie Lady", and 1 "Harpie Lady 2").
"Harpie Queen", "Channeler", "Dancer" and "Harpist" each have an effect that treats their own name as "Harpie Lady" while they are on the field or in the Graveyard. However, since they are treated as their original name in the Deck, it is possible to have up to 3 of each in addition to 3 cards whose name is treated as "Harpie Lady" in the Deck.
In the anime, the "Harpies" are the signature cards of Mai Valentine. She often begins with one "Harpie" card and uses support cards to accessorize and multiply it. Joey Wheeler also used some "Harpie" cards as a reminder of his promise to save Mai from her Penalty Game.
A "Harpie Lady" also appears as a Duel Monster Spirit in Yu-Gi-Oh! GX. She battles Jesse Anderson and his "Crystal Beast Sapphire Pegasus". That same "Harpie Lady" later uses the effect of "Elegant Egotist" to multiply into 3, but they were defeated by "Sapphire Pegasus" and "Topaz Tiger".
In Yu-Gi-Oh! The Falsebound Kingdom, the Harpie Ladies are given names, each based on those of three Harpie sisters from Greek mythology:
- Harpie Lady 1 - Airo (from Aello, "storm swift")
- Harpie Lady 2 - Ocupete (from Ocypete, "the swift wing")
- Harpie Lady 3 - Keraino (from Celaeno, "the dark")
Most "Harpies" in the international release of the game, including all language prints except Japanese, and in the anime have been edited to appear to wear bodysuits while in the Japanese versions they wear much more revealing clothing. "Cyber Harpie Lady" and "Harpie Lady Sisters" have had the spikes extruding from their armor removed due to the suggestiveness. However, some earlier printings of a few of the "Harpie" cards outside of Japan (specifically the original "Harpie Lady" and "Harpie Girl") were printed without being censored.
"Harpies" combine the ability to be rapidly summoned, to destroy the opponent's Spell and Trap Cards, increase each others attack points, enhancing their individual abilities, and to protect each other. They do not have the ability to destroy Spell and Trap cards innately, but their Field Spell Card, "Harpies' Hunting Ground" allows them to destroy one Spell or Trap Card when a "Harpie Lady" card is Summoned in any way. They can be Summoned from the Graveyard in large numbers through the effect of "Hysteric Party". Their support cards, "Harpie's Pet Baby Dragon" and "Harpie's Pet Dragon", rapidly gains power ("Harpie's Pet Dragon") or utility ("Harpie's Pet Baby Dragon") depending on how many Harpie Lady cards you control. Properly played, "Harpies" can overwhelm the opponent in moments with high attack power and powerful effects, but they are not strong individually, so they are vulnerable to opponents who can overpower them, or destroy all of them at once.
Post-Lord of the Tachyon Galaxy, the deck now centered around Xyz Summoning, utilizing cards like "Harpie Channeler", "Elegant Egotist", Summoner Monk", and "Hysteric Party" to Summon multiple Harpies as fast as possible, and perform multiple Xyz Summons (mainly Rank 4 and Rank 7). Some popular Xyz Monsters found in most Harpie decks including, but not limited to, "Ice Beast Zerofyne", "Lightning Chidori", "Number 101: Silent Honor ARK", "Castel, the Skyblaster Musketeer" and occasionally "Number 11: Big Eye" and "Mecha Phantom Beast Dracossack". Some players also include "Blackwing - Zephyros the Elite" to promote their swarming power for more Xyz Summons.
To keep their onslaught running, they also utilize "Hysteric Sign" for searching more Harpie cards and maintain card advantages in their favor, while using "Harpie's Hunting Ground" and "Icarus Attack" as control measures to destroy any obstacles your opponent may utilize.
Due to the change in format, it's recommend to run Link Monsters such as "Greatfly" to not only retain their Xyz Swarming power but to also increase their Attack. Because the deck can swarm very quickly, Link monsters such as “Borreload Dragon” and “Saryuja Skull Dread” can be rather easy to bring out.
Despite the many powerful combos that "Harpies" are capable of, there are still weaknesses within this archetype that can be capitalized on. For instance, most "Harpie" monsters, except "Cyber Harpie Lady", "Harpie Queen", "Harpie's Pet Dragon" and "Harpie's Pet Phantasmal Dragon" are generally low in original ATK, making them unsuitable in battle against most high-ATK monsters.
Since this archetype have emphasis on rapid Special Summoning, anti-Special Summoning cards like "Vanity's Emptiness" and "Fossil Dyna Pachycephalo" can be hazardous against this Deck. "El Shaddoll Winda" can also pose problems as well (albeit "Hysteric Party" can somewhat bypass this).
Most Harpie-based decks relies on either "Summoner Monk" and/or "Harpie Channeler" to Summon more monsters from the Deck, and without those cards, this deck cannot survive for long, nor accumulating speed for offense, which means effect negations such as "Effect Veiler" or "Breakthrough Skill", or disruption cards like "Book of Moon" and "Solemn Warning" is very effective against them during early game stage. Since they mostly focused on Xyz Summons, "Flying "C"" can shut down the Deck's aggressive stance, and "Thunder King Rai-Oh" can blocks the effects of "Hysteric Sign", slowing them down.