During your runs, you can spot white questionmarks on blue planks. They indicate that a random event will occur. There's a slight chance that the event will be Trickster.

He's one of known to us as sylvans or devils. Some call them just fauns. They're notorious pranksters. And because of that, he wants us to play a little game with him. If you accept his offer, you will have to solve a riddle. If you succeed, you're getting a random Treasure for free. If you fail, you're losing one of the Treasures you already had.

Correctly answering the riddle will also result in obtaining the achievement "I Understood That Reference!".

Seems CDPR didn't put as much effort as it looked at first. I realized later that riddle ALWAYS corresponds to GWENT card description. That way we can solve it correctly every time.

That means you can just open this link[www.playgwent.com] and check for description of characters that are given as options to choose from.

Because of this pattern, I'd expect it's highly probable that you can get ANY CHARACTER, which has its own GWENT card, as a riddle description.