Hans requires your assistance once more in "For Whom the Bell Tolls," a main quest centered around Trosky Castle. Your first task is to utilize alchemy to save someone's life. Here's how to prepare Fever Tonic in Kingdom Come: Deliverance 2.
Table of contents
Finding the Fever Tonic Recipe in Kingdom Come Deliverance 2Brewing the Fever Tonic
Finding the Fever Tonic Recipe in Kingdom Come Deliverance 2

The Fever Tonic recipe is located within the Surgeon's Workshop at Trosky Castle. You can access the workshop in two ways. The first involves stealthily entering the premises. The alternative is to persuade the chamberlain with your words, convincing him that you can prepare a digestive potion to relieve his stomach issues. Successfully doing so will grant you entry to the workshop.
If you prefer not to sneak into the kitchen, complete the "For Whom the Bell Tolls" objectives by delivering the horseshoe. Afterwards, return to the forge and talk to Cook Fanka. Offer to assist her with a locked chest, and she will guide you to the noble's kitchen. Once inside, you'll find the chamberlain visibly suffering. Engage him in conversation, inquire about his health, and attempt to pass the necessary skill checks to convince him of your ability to help. This will grant you access to the Surgeon's Workshop. If you already possess or craft both a digestive potion and the fever tonic, returning to the chamberlain with them will allow you to meet Thomas.

Should your persuasion attempts fail, you'll need to steal some food, exit the kitchen, and proceed to the opposite side of the courtyard. Look for another staircase leading to a door on your right, which opens into a kitchen you're permitted to use, though a guard will be present. Speak with the guard and offer him the stolen food; he will then leave his post. From this point, you can sneak upstairs to locate the Surgeon's Workshop. Inside, you'll find his journal on a bookshelf. Take the journal, read it, and use the alchemy station in the room to begin brewing your potions.
Brewing the Fever Tonic

The necessary herbs for this potion are already prepared at the surgeon's station. Simply open the book to the page for Fever Tonicum and begin the process. Follow these steps:
Pour wine into the cauldron.Add three handfuls of Feverfew.Lower the cauldron and boil the mixture for the duration of two sandglass turns.Grind a handful of Elderberry Leaves using the mortar and pestle.Add the ground Elderberry Leaves.Add two handfuls of Ginger.Take a phial from the station's bottom-left shelf, located beneath the wine.Distill the finished tonic using the still.
Don't be discouraged if your first attempt is unsuccessful. You have ample herbs to work with, and more can be found in the chest within the room. Given that you've previously brewed at least one potion, crafting this one should not pose a significant challenge.
This covers everything you need to know about making fever tonic in Kingdom Come: Deliverance 2. Once you have the tonic, your next objective is to reach Thomas. If you gained the chamberlain's trust by making him a digestive potion, return to him with both potions. Otherwise, use the noble's kitchen to sneak up to the chapel where you will find Thomas and his sister, Adele. Speaking with Adele will complete the quest.
