What makes To Mega Therion by Celtic Frost notable?

'To Mega Therion' is significant for its influence on the evolution of extreme metal, inspiring countless bands in the genres of black, death, and doom metal. The album received critical acclaim and helped establish Celtic Frost as a key player in the underground metal scene, notable for tracks like 'Circle of the Tyrants' which became a staple in metal playlists. Released as Celtic Frost's third album in 1985, 'To Mega Therion' marked their transition from a pioneering black metal band to avant-garde metal innovators. This album followed their previous work, 'Morbid Tales' (1984), solidifying their distinctive sound that combined elements of doom and thrash metal.