Clones are standard fare in Magic, and we see new variations of them multiple times a year
Players summon creatures, cast spells, and duel for supremacy using carefully crafted decks
Location 1: Shopkeeper, Near Carsten, Velen: The same shopkeeper that Geralt acquires Schirru from will sell the following cards: Card 1: Foltest, Son of Medell (Northern Leader) Card 2: Emhyr var Emreis, Invader of the North (Nilfgaard Leader) Card 3: Gaunter O'Dimm: Darkness [2 of 3] (Neutral) The second and third copy of this card can be found here, but only upon subsequent visits
[1] If your opponent Normal or Special Summons a monster: You can Special Summon this card from your hand, then you can Fusion Summon 1 "Melffy" Fusion monster using materials from your hand and/or field
I have a basic strategy, which I laid out in my Top Five Deck-Building Tips for Beginners