"I think if they want an exact result, they pick an exact god, but they can generally ask them all. Whoever may be listening. A contact of mine in Solvunn is willing to put together a pantheon of the gods for us."

This is important to him, because so far he has come up empty with the extent of Thorne knowledge. One of the things he hates the most is willful ignorance. It so often comes with arrogance, to think some knowledge is useless. As a scholar, he believes no knowledge is fully useless. Sometimes he feels like he's living with the Brotherhood all over again, trying to convince them of the same things.

"The only way they were able to take the illusions off of the island was by knowing what god they did the spell to. High Magic is more powerful than people thought."

All the power of the Thornean mages and they were blind to this until they were talked around to the truth. It required the Summoned to shake them until they had the people they needed to break down the illusions. Yennefer managed to do exactly that, he's certain she was even more frustrated than he is about it.