To embark on a spirit quest you need magical elixir. Just mix stamina potion with some strength powder and you are good to go.
This is the low-spoiler guide for "Spirit quest elixir" puzzle in The Darkside Detective. Unlike in normal walkthrough, you get gradual hints on how to solve the puzzle. Click the big button below to see your first hint. If the hint contains a spoiler, you will be warned about it before clicking.