Cannot be Normal Summoned or Set. Must first be Ritual Summoned. You can Ritual Summon this card with any "Gishki" Ritual Spell Card. Once per turn: You can discard 1 "Gishki" monster to target 1 face-up card your opponent controls; shuffle that target into the Deck.
Gishki Aquamirror is currently the best Ritual Spell card for Gishki ritual monsters. It can recycle itself from the Graveyard to your Deck, at the same time you can also recycle 1 Ritual monster from the Graveyard back to your Hand as well.
Forbidden Arts of the Gishki is a powerful Ritual Spell card to use your opponent’s monsters as tributes for your Ritual Summoning instead, but the drawback is your Ritual Monster’s ATK is halved and you cannot conduct Battle Phase during the same turn.
Gishki Photomirror is only an option if you are able to heal. Because summoning a level-8 monster like Evigishki Soul Ogre will require your entire starting LP.
Gishki decks have a lot of ritual support due to the playstyle of their archetype. Gishki Shadow can be used as the entire cost of a Ritual Summon and can be discarded to search Ritual Spells. Gishki Ariel can search any Gishki monster including the Ritual monsters. Gishki Chain adds Ritual monsters or Spells to your hand.