You need to look up in which order the three voodoo items VG wants to have should be used.
This is the low-spoiler guide for "Voodoo item usage order" puzzle in Gibbous - A Cthulhu Adventure. 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.