Ex Deo is a Canadian death metal band formed in 2008 in Montreal, Quebec. The band is a side project of Kataklysm frontman Maurizio Iacono, based on the history of the Roman Empire.
Ex Deo was formed in 2008 as an artistic project Maurizio Iacono was really interested in and as it caught on, it became more of a band. However, Iacono said in an interview that Ex Deo will not be as active as Kataklysm is.
“ Ex Deo is more of a prestigious type of band. We're not going to tour intensively for it, we're not going do as much as we do for Kataklysm. Kataklysm is a world-warrior band, you know. It's on the road constantly and more in touch with social aspects. This (Ex Deo) is more something artistic, you know. ”

—Maurizio Iacono-

Ex Deo's debut album Romulus was released through Nuclear Blast Records on June 19, 2009 in Europe and was released on June 30, 2009 in North America. The album was recorded with producer and Kataklysm guitarist Jean-Francois Dagenais, featuring guest appearances by Karl Sanders (Nile), Obsidian C. (Keep of Kalessin) and Nergal (Behemoth).

Ex Deo's second album will be called Caligula after the famous bloody Caesar. It will start pre-production in 2011 after Kataklysm's world tour for Heaven's Venom

Source : http://en.wikipedia.org/wiki/Ex_Deo