There more than one bands with this name:

1. Summoner, Formerly known as Riff Cannon, are a heavy rock band from Boston, USA. The quartet has released a debut album entitled "Phoenix" (2012). They play a heavy blend of Psych, Sludge, Stoner, Doom, Space Rock to outstanding effect. In 2013, the band released their second album, Atlantian.

2. Black metal band from Italy. Summoner started in January 2001, after the Death Seagull’s Scream dissolution, with Giorgio Beltrami, Stefano Magni and Massimo. Soon, they change the female vocalist for Paolo Cattaneo. The line-up was completed discovering bassist Luca Ciusaniat.
They released an EP in 2002 titled Summoner's Sign and a full length album in 2003 titled Winter Solstice. Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.