From GameWatcher: “Slay The Spire has got an abundance of weird, offbeat relics and items that can be completely overpowered, if you’ve built your deck to support them. The matter of combining all the moving parts just right is what usually comes in the way, though, and this goes for the Pocketwatch, too.”
Source: N4G PC Slay The Spire Pocketwatch Guide – How to Get It?