This is just the result of various collections of information, you don't have to do it to get a competitive deck. Read the descriptions of the cards before creating them, to see if they can match the decks you want to have.
With this expansion, several versions of the Demonist decks coexist. Two Galakrond decks, including a Zoo, and a Handlock share the field with equivalent Win Rates.
Dragonblight Cultit, Fiendish Rites and Veiled Worshiper are instant additions to all Galakrond versions, always in duplicate, while Nether Breath and Crazed Netherwing are played in all versions, due to their extremely interesting effect. Finally, Dark Skies, although more interesting in the Handlock version, can be used in both versions to help you regain control of the board.
Present only in the Handlock version, Valdris Felgorge and Abyssal Summoner aren't obligatory to craft if you don't want to play the deck of which they are two big pillars.
The new Hearthstone extension, Descent of Dragons, is available since December 10. Here is our selection of decks made by professional players or streamers, to have fun once your boosters are open.