What does this 'Bottomless Carafe' do?
When he meditates, Geralt consumes one "Strong Alcohol" to replenish all bombs and potions.
What the bottomless Carafe offers is never needing a "Strong Alcohol" to restock your alchemical items.
Given to you by Gaunter O'Dimm as a reward for a certain story path.
The choices given by Gaunter determine the reward:
- Wanna be as swift as the wind. Caparison of Lament - The saddle appears to be fashioned of strange leather, the hide of some unknown beast. As evidence of its unusual nature, suffice it to say that it is always rather warm to the touch. The saddle addles the mind of a randomly-selected opponent within a limited range. Transforms Roach into a black horse with red eyes, black smoke particle effect. Has Axii and stun effects on nearby enemies.
- Never wanna go hungry again. Horn of Plenty - Provides an endless supply of food. The horn of plenty seems alive and pulses while producing food. Endless food item useful for health regen.
- A bottle of vodka that's always full. Bottomless Carafe - Provides an endless supply of hard alcohol. The spirit is distilled from scorpion tails. Endless supply of alcohol used when meditating to replenish alchemy items.
- Make me rich. 5,000 crowns
- Don't want anything from you. You get nothing.
The player is likely to be overflowing with alcohol, food, and crowns late-game, it seems the best choice would be the saddle.
Credit to the Witcher wikia for item information and journal descriptions.