Complex sentence: Periphery was formed by guitarist Misha Mansoor in 2005, who slowly gained a reputation on the Internet via a regularly-updated Soundclick account, the Meshuggah and John Petrucci forums, and the sevenstring.org message boards.
Split into simpler sentences: Periphery was formed by guitarist Misha Mansoor in 2005. He slowly gained a reputation on the Internet, primarily via a regularly-updated Soundclick account, Meshuggah and John Petrucci forums, and the sevenstring.org message boards.