I finally know where to find all Gwent cards I wanted to shere this here. However, I have listed only the Hero cards.
Neutral Cards
- "Geralt of Rivia" to find during Gwent-Quest "old buddy" in Novigrad, in seven cats inn;
- To find "Yennefer of Vengerberg" during Gwent-Quest "game with the host" of Stjepan, Alchemy inn, Oxenfurt;
- To find "Cirillia Fiona Elen Rianno" ( Ciri / the Lion Cub of Cintra) during Gwent-Quest "big city player" by Scoia'tael dealer and warehouse, Forest of Novigrad (west of Ferneck, in the forest);
- "Triss Merigold" during Gwent-Quest "old buddy" of Lambert, nowhere inn;
- "Avallac'h" during Gwent-Quest "After Skellige Style from Gremita, in Gedyneith, Ard Skellig;
Nilfgaard Cards
- To find "Letho of Gulet" during Gwent-Quest "players from Velen" of boatbuilders, in Oreton ;
- "Menno Coehoorn" to find during Gwent-Quest "game with the host" host, inn at the crossroads;
- To find "Morvan Voorhis" during Gwent-Quest "big city player" by Marquise Serenity, Passiflora;
- To find "Tibor Eggebracht" during Gwent-Quest "game with the host" of Olivier, the innkeeper, kingfisher;
Scoia'tael Cards
- To find "Eithne" during Gwent-Quest "old buddy" of Zoltan, rosemary and thyme;
- To find "Saskia / Saesenthessis" during Gwent quest "Old Pal" by Vernon Roche, Temerian Resistance Camp;
- To find "Iorveth" during the side quest "shock therapy of Druid, at Gedyneith, Ard Skellig;
- Monster Cards
- To find "Draug" during Gwent-Quest "After Skellige Style ' Crach an Craite on Ard Skellig
- Win "Kayran" of traders or craftsmen, accidental;
- Win "Imlerith" of traders or craftsmen, accidental;