Charmer

The Charmer cards, known as Spirit Envoys in the OCG, are a series of Spellcaster-Type monsters of different Attributes. As their names suggest, each version possesses various effects depending on the creature's attribute. The first monsters represent young magicians with their familiars, the second are the same magicians, albeit slightly older looking, but with a blank look and a monstrous version of their familiar and the third are grown-up versions of the magicians. Originally, there was no DARK charmer, but it was released in The Duelist Genesis, after the third cards for each other Charmer was released. There is, as of now, a LIGHT Charmer, released in The Shining Darkness.

The first cards, each named as "[Name] the [Attribute] Charmer", released in The Lost Millennium, are Flip Effect Monsters that take control of an opponent's monster of the same attribute as the charmer's.

The second cards, each named as "Familiar-Possessed - [Name]", released in Elemental Energy, are monsters whose effect is activated when you tribute one of the first cards with another attribute-matching monster on your side of field. If Special Summoned this way, the familiar-possessed charmer will gain the piercing effect. Otherwise, they can be Normal Summoned as usual. There is no Familiar-Possessed version of "Lyna" or "Dharc".

The third cards, each named as "[Adjective] [Name]", released in Enemy of Justice, are effect monsters that allows you to Tribute a monster to Special Summon another monster from your hand of the same attribute as the Charmer and the Tributed monster. However, should the charmer be destroyed, so are the monsters Summoned by its effect. The third forms are not stronger than their Familiar-Possessed forms, but are only 300 points stronger than their first form.

This series also has a few Trap Cards called "Spiritual Art", which allows you to Tribute an attribute-matching monster on your side of the Field for an attribute-related effect such as inflicting damage or returning cards to the Deck.

No second cards have come out for "Dharc" or "Lyna" yet. There is a support card similar to the "Spiritual Art" Traps for the Dark Attribute, "Dark Spirit Art - Greed", and while it was released before "Dharc" and doesn't depict the corresponding Charmer in its artwork, its cost and Japanese name are appropriate for the series.

Charmer Deck
A good way of making sure your opponent has monsters of the desired Attribute is by using cards that changes them to the desired one,ex.: "DNA Transplant" or "Scroll of Bewitchment". Then you can use the monster you just got from your opponent to Special Summon the Familiar-Possessed or use them for the Charmers Trap Cards. One good strategy is placing the Charmer monster face-down, then using "Scroll of Bewitchment" to change the enemies monster attribute, Then using "Book of Taiyou" to flip the Charmer and take the monster. The use of "Stumbling" is also recommended as your opponent will Summon to try and attack next turn. Also the use of the Extra Deck is a possibility, with cards like "Tempest Magician" and "Explosive Magician".

Trivia

 * The original Four Charmers, "Aussa", "Eria", "Hiita", and "Wynn", were first released in The Lost Millennium. Two packs later, they had their Familiar-Possessed forms released. Two packs after that, was their final forms. Dharc and Lyna, however, do not follow this trend of having their advanced forms come two packs later.
 * The person that made the designs for the Charmers (and some other card designs that are hard to mention) is Akina Fujiwara, though she did not draw their final forms.
 * "Raging Flame Sprite", "Whirlwind Prodigy" and "Night's End Sorcerer" appear to be drawn by the same artist but aren't considered Charmers.
 * It is possible that, with the release of Duel Terminal - Raid of the Inverz!! and onwards, that the Charmers, mainly "Eria" and "Wynn", are part of families consisting of other Archetypes, such as "Eria" and the Gishki and Wynn with the Gusta. However with the release of Generation Force there is a possibility that the other charmers may have not joined an archetype and and remain solo as seen in the possible new "Lyna" card "Mira the Eternal Magician".
 * The newest packs have begun releasing new incarnations of the Charmers, with "Gishki Erial", "Wynnda, Priestess of Gusto", and "Mira the Eternal Magician" bearing obvious similarities to the original versions of the Charmers, even wearing their original outfits with some additions. Whether new versions of the remaining Charmers will be made to match has yet to be seen.
 * Many fans speculate that "Elemental Mistress Doriado" is a teacher-like figure to "Aussa", "Eria", "Hiita", "Lyna" & "Wynn", as she is LIGHT, but also treated as FIRE, WATER, EARTH and WIND.
 * Surprisingly (in their original sets), "Dharc's" serial number for The Duelist Genesis is 26, same as "Aussa" for The Lost Millennium. All the Charmer's numbers are "Lyna" being TSHD-EN24, "Aussa" being TLM-EN26, "Dharc" being TDGS-EN26, "Eria" being TLM-EN27, "Hiita" being TLM-EN28 and "Wynn" being TLM-EN29. This order gives 2 number 26's but skips number 25.
 * Also Notice that their Familiar-Possessed Forms have the same Number as their Charmer Forms
 * Note that all the Charmers (originally) (not Familiar-Possessed) came in the packs that only start with "The." The Lost Millennium, The Duelist Genesis, and The Shining Darkness are the only TCG sets that start with "The" and are the only sets that released the six Charmers.
 * If one were to study the cards closely enough, it is entirely possible for the "Story" of the Charmers to be discovered. Their story being, that it is possible they sacrificed their lives with the Spiritual Art's, to stop some unknown force, and their bodies being Taken over by their Familiars to continue to fight, as they seem to be wearing the Ribbon of Rebirth while in this form. Then be reincarnated later on after they have truly died/The Familiars Magic power have run out, like Eria being reincarnated into Erial, however, Lyna and possibly Dharc could be the only exceptions, as they have yet to have a Familiar-Possessed form and Spiritual Art card.
 * This could also be a part of the story. Dharc and Lyna are both wearing handcuffs, so they could have been 'released' into the world as new magicians, perhaps to carry on the other charmer's legacy.
 * Or the whole reason for what happened to the original Charmers, was to save Dharc and Lyna from some kind of prison.