(Getty Images)

The Satanic Temple in Ottawa plans to hold what apparently will be the first public Black Mass in Canada's history on Aug. 17.

A Black Mass is an inversion and mockery of the Catholic Mass, where the ritual is performed in reverse, from the end to the beginning, and symbolizes the undoing of Christ's sacrifice on the Cross and the undoing of Satan's defeat.

"Essentially, it involves using traditional symbols and inverting them to create a ritual that is meant to be the opposite of the traditional Mass," Nicolas Marc, the national coordinator of the Satanic Temple, told Global News. In a real Black Mass, a consecrated Communion host is used but Marc told LifeSiteNews that in this ritual a consecrated host would not be used.

(Screenshot, Facebook)

The event takes place at The Koven, a heavy metal restaurant/bar with a Satanic atmosphere. Admission is $20, or $15 "with a donation of clean socks" for a charity drive. Pre-registration online is required, no photos or videos are allowed at the Black Mass, and the doors open at 10:00 p.m. (As this story was posted, tickets for the Black Mass reportedly were sold out.)

The ceremony is entitled Libertas in Tenebris, or Freedom in Darkness.

"The Black Mass is a sacrilegious ceremony structured in imitation of the Catholic Mass," according to the National Catholic Register. "Invoking Satan, the ritual is centered around the desecration of the Eucharist, which is generally done by stealing a consecrated host from a Catholic church and using it in a profane sexual ritual or defecating and urinating on it."