To complete it, you must collect every single card of each type; a total of 120 cards, from the 199 available cards. The other 79 cards are duplicates (for example, there are three “Ghoul” cards you can find, but you only need one for this quest objective). 
- Northern Realms Gwent deck (40 cards)
- Nilfgaardian Empire Gwent deck (41 cards)
- Monsters Gwent deck (44 cards)
- Scoia'tael Gwent deck (41 cards)
- Neutral Gwent cards (29 cards)
Gwent cards may be obtained by purchasing them from merchants, winning against others at Gwent, and by winning against named NPCs in Gwent side quests. After winning against a certain number of generic merchants, playing against merchants will no longer earn new cards. The book A Miraculous Guide to Gwent (added by patch 1.20) can be used to keep track of the number of cards still necessary to obtain, and of Gwent side quests.
Missable Cards Edit
Throughout the game, some cards are easily missed if a player chooses one action over another, chooses to skip a side quest, or just by not exploring. Here's a list of such cases:
- Do the side quest A Matter of Life and Death. There'll be a small Gwent tournament going on in the main courtyard where you'll need to win all the rounds to get all the cards.
- Do A Deadly Plot. Turns out the one you're looking for is a big gwent player and has one of the best cards in the game.
- Do A Dangerous Game and take the cards as your reward.
- Participate in High Stakes. You must win the tournament to get every card (see main quest page for tips).
- Do Shock Therapy to get the Iorveth card.
- Free the Claywich merchant who is held captive southeast of the Boatmakers' Hut. Be careful as this merchant is bugged. Make a save just before opening his cage, then make a fast travel to Claywich. If the talking option doesn't show up, reload until it does. (Done with Patch 1.22) Make sure to buy all the gwent cards he has for sale.
- Play Lambert as soon as you can (either at The Nowhere Inn or at Kaer Morhen when the witchers are drinking)
- See this list for a breakdown in missable characters/cards, making sure to play (or buy from) each one as soon as you can to avoid missing their card later. Patch 1.05 added in fail-safes if you missed a player's card.
Journal entry Edit
- In his previous adventures, Geralt had gained fame as a master dice poker player. Yet having mastered all challengers in this arena, he had no choice but to find another in which to garner more laurels. He thus decided to take up gwent, and since he aimed to play at the highest levels, he felt he had to gather a complete collection of all the cards available – including some which could only be had by winning them off the best players around.
- Complete your collection of Gwent cards.
- This quest does not require the collection of Gwent cards added by the expansion packs.