GWENT: The Witcher Card Game

I unlocked this achievement while crafting cards in the inventory, so you can get them through kegs and crafting.

This will definitely unlock through natural playing, as it's not as daunting as it sounds. If you're in a hurry to unlock it, here is my recommendation:

Complete the tutorial. It will give you rewards that start you with plenty of cards. Open any kegs you have in the shop. After that, go to the deck builder, filter by "Owned" and by Kingdom, and figure out which deck you have the most cards in. Now prioritize that deck until this achievement is done.

There are two different types of cards: Normal and Premium. Premium cards are not "spend real money to get these" cards. The Normal cards are still images, while Premium cards are animated. Both count towards this achievement.

The Normal cards are obviously cheaper than Premium cards (i.e. 80 Scraps vs. 400, 200 vs. 800, etc.). If you're hurrying to get this achievement done, and/or you have a ton of scraps ready to go (I did, but I played the beta quite a bit), just start crafting away. For me, I had 25 Nilfgaard cards already, so I only needed 25 more. I started browsing through Nilfgaard cards and crafting the cheap ones I didn't own. If you set your filter to "Unowned," you can find which ones you still need, and you can browse through cards by pressing Left or Right while inside of the crafting menu, instead of having to back out each time.

Unfortunately, if you're low on Scraps to craft new cards, the only real way to get them is by grinding multiplayer matches. You can get them through Rewards and by Milling(destroying) duplicate cards too, but it's pretty slow.