Guitar Overdrive pedal effect. Conceived in the dark depths of Kirk Hammett's mind and forged in the secret laboratories of KHDK, an iconic circuit has been perfected to achieve its full potential and create the ultimate tone, with all the control in your hands. The Ghoul Screamer is a multipurpose pedal, a true utility knife of overdrives, featuring three standard controls and five additional switches. The Ghoul Screamer was engineered to work excellently with any guitar, amp, pedal & pickup setup.