Gishki

Gishki, known as Ritua in Japan,their team symbol is a blue sapphire mirror that all the members wear, usually around their necks or on their staves. The Ritual Monsters (and, starting with "Merrowgeist", Xyz Monsters) of the group all have "Evigishki" at the beginning of their names, with the name of the kind of creature they've become (usually an Ogre) at the end.
Their Japanese name, "Ritua", is a corruption of the English word "Ritual", used in the TCG terms "Ritual Spell Card", "Ritual Summon", and "Ritual Monster".
All known "Gishki" monsters are WATER, and many are Spellcaster, Sea Serpent, or Aqua. Their playstyle is focused on Ritual Summoning and either searching and returning cards to the Deck.
"Gishki" is a unique archetype, since it has not just one or two, but THREE Ritual Spell Cards for a specific archetype. They are "Gishki Aquamirror", "Gishki's Duplicate Soul Mirror", and "Forbidden Arts of the Gishki". "Gishki's Duplicate Soul Mirror" in particular is very unique, as it is the first Ritual Spell card that allows you to use Life-Points instead of Tributes for the Ritual Summon, allowing an easier way to call "Gishki" Ritual monsters.