In Kingdom Come: Deliverance 2, Hans's main quest, "For Whom the Bell Tolls," requires crafting a Fever Tonic to aid Thomas. This guide details obtaining the recipe and brewing the tonic.

Locating the Fever Tonic Recipe:

Access to the Surgeon's Workshop in Trosky Castle, where the recipe resides, can be gained in two ways:

1. Stealth: Sneak into the workshop.
2. Diplomacy: Persuade the chamberlain to grant access by offering to create a digestive potion. Success hinges on passing skill checks. Failing these checks necessitates stealing food, bribing a guard, and then sneaking into the kitchen via an alternate route. This leads to the Surgeon's Workshop.

Regardless of your method, the Surgeon's journal containing the recipe is located on a bookshelf within the workshop.

Brewing the Fever Tonic:

The necessary ingredients are already present on the surgeon's workstation. Follow these steps:

1. Pour wine into the cauldron.
2. Add 3 handfuls of Feverfew.
3. Lower the heat and boil for 2 turns of the sandglass.
4. Grind a handful of Elderberry Leaves using the mortar and pestle.
5. Add the ground Elderberry Leaves.
6. Add 2 handfuls of Ginger.
7. Obtain a phial from the bottom-left shelf.
8. Distill the tonic using the Still. Multiple attempts may be necessary.

Completing the Quest:

After brewing the Fever Tonic, locate Thomas. If you gained the chamberlain's trust by providing the digestive potion, return to him with both potions. Otherwise, use the kitchen to access the chapel and find Thomas and his sister, Adele. Speak with Adele to conclude the quest.