Horseback is one of the most unique metal based artists in the past few years. Taking influences atmospheric sludge metal, psychedelic rock, drone, post-rock, black metal, and ambient.
Mainly listeners fell head over heels for The Invisible Mountain (which I don't blame them since it's an incredible album) but shunned their ambient work, though their first release is Impale Golden Horn back in '07. The Invisible Mountain followed up a couple years later and a year later they released another drone ambient album, Forbidden Planet, then a year later they did the collaboration with Pyramids (which is a drone ambient album) and released a more rock/metal song on the split part. Overall Horseback is more of a drone and ambient band than a rock/metal band.
On Half Blood though it blends all of Horseback's styles, which is like mix of Neurosis, Earth, Burzum, and Popol Vuh...
The first two tracks are that awesome blackened psychedelic stoner post-metal/rock songs which everyone loves. Then it really hits the left-field with the first ambient and drone track, Inheritance. The next song, Arjuna, is the more rock/metal kind like the first two tracks, but one part has some clean vocals which sound like someone on Sesame Street... Though still a good song. The last three tracks are all drone and ambient songs, which I'm sure people will complain about... I have to say these are their best ambient and drone songs to date. I mean The Gorgon Tongue compilation is great, though these four drone and ambient tracks are awesome, especially the last two tracks. Hallucigenia III, the last song on the album which clocks in at twelve minutes is actually gorgeous, and even uplifting song, it's a great way to end Half Blood.