“He’d call me at four in the morning and leave a 15-minute guitar solo on my voicemail”: Serj Tankian on his collaborations with the enigmatic Buckethead

“He’d call me at four in the morning and leave a 15-minute guitar solo on my voicemail”: Serj Tankian on his collaborations with the enigmatic Buckethead – and the time they played a high school battle of the bands together