Wonderful news! Jaskier will offer his aid, if he can give it, as he has some mild healing magic himself, but he can also produce a food that will purify any toxicants in one's system. He would be glad to offer this to Retha to take to Cassia, or he can present them himself.

Considering they're speaking of Cassia and Umber, he will take assumption that this does have to do with the cracked tank and its sabotage. The raven will question if Firewing knows who, or what, broke the tank.