basis for the stories, with the third, The Fatal Strand, referencing this source, Odin and Yggdrasil (or in-world versions of) featuring significantly in the plot. Witches of East End by Melissa de la Cruz is about immortal witches that are actually Norse gods, including the goddess Freyja, Loki and Balder The Ragnarök Conspiracy by Erec Stebbins (2012) is a contemporary thriller centered on a plot by terrorists to instigate a global war between Western and Islamic nations. It contains references to Old Norse, Norse runes such as the Elder Futhark, and Norse mythology including the events of Ragnarök. Rick Riordan has started Magnus Chase and the Gods of Asgard (2015), a trilogy based on Norse mythology set in the same universe as his Camp Half-Blood Chronicles. Music Norse mythology influenced Richard Wagner's use of literary themes from it to compose the four operas that make up Der Ring des Nibelungen (The Ring of the Nibelung). Mats Wendt based his neo-romantic 16-hour symphonic suite Eddan on the chronological reconstruction of the Norse myths by Viktor Rydberg. Burzum is a Norwegian Black metal band whose lyrics and imagery are often inspired by Norse mythology. Its founder Varg Vikernes has also written many books about Norse mythology and is an outspoken Pagan. Norse mythology is a recurring theme in Heavy metal music lyrics. Manowar has numerous releases referencing Norse mythology. Besides the 2007 concept album Gods of War, there are songs Gates of Valhalla (Into Glory Ride, 1983), Blood of My Enemies and Kill with Power (Hail to England, 1984), Thor (The Powerhead) (Sign of the Hammer, 1984), The Crown and the Ring (Kings of Metal, 1988), and Swords in the Wind and Fight Until We Die (Warriors of the World 2002), and Righteous Glory (The Lord of Steel 2011). Swedish Symphonic metal band Therion based many of its lyrics on Norse mythology, including the whole 2001 concept album Secret of the Runes. The Viking metal music genre focuses on Viking Age and Norse mythology as inspiration for lyrics. Examples include Bathory, Falkenbach, among others. A broader definition of Viking metal may also include Viking-themed or Norse-themed Folk metal (Turisas, Ensiferum, Finntroll, Týr), Doom metal (Doomsword), and Death metal (Amon Amarth). Norwegian symphonic metal band Leaves' Eyes released Vinland Saga concept album (2006), based on Saga of Erik the Red and Njord (2009), based on Norse mythology in general. German Heavy metal band