Panic Attack is a song by progressive metal band Dream Theater from their 2005 album Octavarium.
This song is one of the most difficult in the game, so much so that Harmonix guarantees that it will give you a panic attack.
The song is over 7 minutes long and switches time signatures among 4/4, 3/4, 2/4, and 5/8. The bass opens up this song, followed by the guitar, both of these instruments opening with a faster, slightly different version of the main riff of Painkiller. In the middle of the song is a long instrumental break which contains a synth solo where the guitar is played behind it, but these "backgrounds" are nothing to be scoffed at, for the guitar solo explodes out of nowhere and zips by hitting the expert guitarist with hammer-ons that keep coming to the end of the solo. The drum part is loaded full of bass pedal, especially in the outro, just before the song ends.
The vocal part is also hard, but nowhere near as hard as the other difficult vocal songs such as Tangled Up in Blue.