The Svengali Deck of cards is a specially constructed deck that can be used by magicians to perform various card tricks. The deck and the tricks performed with it is self-working and require almost no skill. It is based on an old principle that can be found in The Discoverie of Witchcraft and Clever and Pleasant Inventions (both from 1584), and which is commonly known as the Blow Book.
The deck can be dribbled or riffled to create the illusion that the deck is completely ordinary. It can even be shuffled. The trick involves a spectator choosing a card from the deck and returning it; the card can appear practically anywhere in the deck, making tricks like the Ambitious Card incredibly simple. The final and most stunning trick is when all the cards are suddenly presented as being all the same card as chosen.
Burling Hull was advertising a deck with this same mechanics in the February, 1909 issue of the Sphinx as "Cards Mysterious," and two years later, in his book Sealed Mysteries, he claimed it as his invention that he had copyrighted. In between the initial advertisement and Hull's subsequent claim, a description of the idea appeared in Ellis Stanyon's New Card Tricks, 4th Series in 1910 as the "Third Arrangement" of The Fin de Siecle Magic Pack of Cards.
W. D. LeRoy appears to be the first sell it as the name "Svengali", which comes from George du Maurier's 1894 novel Trilby where Svengali is a fictional hypnotist in the novel.
This deck is also sometimes referred to as a Long and Short Deck and in Europe as the Radio Deck.
Two-Way Svengali Deck and the Three-Way Svengali Deck are used to force more than one card by using different "banks" of duplicate cards.
- Joe Stuthard's Trilby (1949) and Bi-Co Trilby Decks are variations on this deck. In the 1960s and 1970s, Marshall Brodien sold millions of Svengali decks under the name TV Magic Cards.
- Joe Berg's Novel-Gali Deck which, in addition to the changing faces, added a color changing back.
- Al Stevenson's Blanka Deck using blank cards.
- Ralph W. Hull's Mirage Deck which adding the rough-and-smooth principle.
- Theodore DeLand also incorporated the Svengali Deck principle into a version of his Inverto so the deck could be displayed