I'm on the Roche path and Geralt is supposed to be helping Dethmold do the necromancy ritual. When Dethmold asked Geralt if he is ready Geralt says he needs time to prepare then says Gadwell should do it.

I can't trigger the ritual. Who is Gadwell?

It is the name of a potion. You need to drink it, and then speak to Dethmold again.

If you don't have the formula, Myron should have it in stock. While Dethmold is preparing for the ritual, you can usually find Myron sitting on a bench just outside the tent.

Well! Thank you both for this information (which I'm sure is in the manual and I didn't look!)

I originally thought I couldn't do this ritual because Geralt didn't sell Margna's notes about necromancy to Dethmold.

Thanks to both of you for the quick response!!

You're welcome. :)