Much as Ciri tends to be in combat and with magic, she's not particularly patient when it comes to making her own move. Rather than giving it a moment to try and think of what Yennefer might do next, she's quick to play her own card. It's the not the best of her mediocre starting hand, but she's hoping the confidence with which she placed it might give that illusion. She doesn't anticipate mercy from Yennefer and doesn't even think she can realistically outsmart her. But perhaps she might. If she can seem as though she's only tasted victory because Jaskier doesn't always play as aggressively as he could maybe she can throw Yennefer off enough to pull out a victory.

That's the hope, at least.