Examples of power metal bands include DragonForce, Blind Guardian, Helloween, Sonata Arctica, Angra, Sabaton, Stratovarius, Kamelot, Rhapsody of Fire and HammerFall. Progressive metal is a fusion between progressive rock and heavy metal. It is one of heavy metal's more complex genres, due to its use of unusual and dynamic time signatures, long compositions, complex compositional structures, and skilled instrumental playing, where instrumental solos are detailed and extended. However, the latest age of progressive metal has favored rougher lyrics and lower-pitched riff sequences with high amounts of strumming. Vocals, if present, are melodic (though there are a few that utilise unclean vocals), and lyrics are often philosophical, spiritual, or political. Many bands of the genre were influenced by the progressive rock bands Rush and King Crimson, who would often incorporate elements of heavy metal into their music. Examples of the genre include Queensrÿche, Dream Theater, Opeth, Tool, Fates Warning, Mastodon, Gojira and Pain of Salvation. Djent, also known as djent metal, is a musical subgenre that emerged as a spin-off from progressive metal. The word "djent" is an onomatopoeia for a heavily palm-muted, distorted guitar chord. Typically, the word is used to refer to music that makes use of this sound, to the sound itself, or to the scene that revolves around it. Djent as a style has been described as featuring heavily palm-muted, distorted guitar chords alongside virtuoso soloing, and is characterized by rhythmic complexity and palm-muted riffing. Pioneering bands in the style are Born of Osiris, Meshuggah, Periphery, Animals As Leaders, Tesseract, and Textures. Space metal blends progressive metal with space rock. Arjen Anthony Lucassen's Star One is the main pioneer of this genre with their album, "Space Metal". Progressive metalcore (also called technical metalcore or ambient metalcore) is a fusion of progressive metal and metalcore characterized by highly technical lead guitar, "atmospheric" elements, and complex instrumentation. Some notable practitioners take influence from djent. Speed metal originated in the late 1970s and early 1980s out of the new wave of British heavy metal, and was the direct musical progenitor of thrash metal. When speed metal first emerged as a genre, it increased the tempos that had been used by early heavy metal bands, while retaining their melodic approaches.