Hello there, this is when I overkill this boss for the first time. :]
How to get: If you have I Just Wanna Burn, it will work, if you dont have I just wanna burn, the "Thing" will not appear. 1. At song select, some kind of purple skull will appear at a random song. 2. Play it, and get atleast bronze. 3. Go back to song select, play the next random song with the skull, or what it is. 4. Get atleast bronze on it, too. 5. Go back there, and play the next song. 6. Get atleast bronze. 7. If you've done it right, the skull will appear at "I just wanna burn", so when you start playing I just wanna burn, then the boss appears in the classic message 8. Complete the boss.