SYSTEM OF A DOWN, SLIPKNOT, MARILYN MANSON and LAMB OF GOD are the first confirmed bands for the Heavy T.O. and Heavy MTL festivals, set to take place August 11-12, 2012 at Downsview Park in Toronto, Ontario, Canada and at Parc Jean-Drapeau in Montreal, Quebec, Canada, respectively.

The complete lineup for both festivals will be revealed at noon tomorrow (Friday, March 16).

Source: Blabbermouth.net