After Tjodalv left Dimmu Borgir in the middle of March 1999, he started to concentrate fully on Susperia together with old-time friend Cyrus.

They recorded a demo, Illusions of Evil, in December 1999 at Pitfire Studio outside Oslo, which was mixed and mastered by L. Argedick.

In March 2009, it was reported that vocalist Athera (real name Pål Mathisen) had suffered a heart attack.

Testament, one of the members' favorite bands,[9] was a major influence, and by the time the album Unlimited was released, the black metal elements had disappeared.

Susperia is not a Satanic band, though their lyrics tend to criticise and question the views and morals of Christianity.