Road Rage is the final power up you unlock via Blitz Cred.
Road Rage is a power that uses your Overdrive meter, so hit white notes to charge it up. Road Rage causes a car to fly out of nowhere and start crashing into random notes, giving you points for every note it hits. Press X to deploy Road Rage when you have sufficient Overdrive meter.
To get this achievement, your car must destroy at least 25 notes with Road Rage over the course of the ENTIRE run through the song. This does NOT require you to destroy 25 notes with a single deployment of Road Rage. This is not a particularly difficult feat and should be easily attainable on songs in which Road Rage is an effective choice.
Road Rage is most effective on songs with high note volume, during sections where multiple tracks are highly active simultaneously like most metal songs, and this achievement is easier to attain on longer songs which permit you more uses of Road Rage over the course of the song, and thus more opportunities to hit notes and get the 25 required.
"Cult of Personality" is included with Rock Band Blitz and is an easy song to get this achievement on, largely in part to the high volume of notes and the length of the song. Spam Road Rage every time you have the meter and you will assuredly hit the 25 by the end of the song. The achievement will pop up immediately when the 25th note is hit, during the song.