Blood for the blood god is part of the popular battlecry of Chaos Space Marines in Warhammer 40K, sometimes followed by the words “skulls for the skull throne”.
Online, the phrase served as the inspiration for many memes, appearing as the caption of image macros, as well as the template of humorous phrases
The first edition of Warhammer 40K was published in September, 1987, featuring the Chaos Space Marines faction, who worship Khorne, a god of chaos.
In the fantasy world, Korne is a god associated with war, homicide, anger, hatred and blood, which spanned the battlecry of Chaos Space Marines; “blood for the blood god!”.
An early explanation for the battlecry was added to the Wikia page of Khorne in 2006.
The phrase first appeared on a meme in 2008, appearing on a demotivational poster posted on gamereplays.
It would appear on rage comics as well as a variety of image macros in the following years, while gaining popularity on Reddit and Twitter as a snowclone.