Seven Against Thebes
In "Seven Against Thebes" by Aeschylus, the seven warriors slaughter a bull over a black shield and then "...touching the bull's gore with their hands they swore an oath by Ares, by Enyo, and by Rout [Phobos]". According to Stesichorus Ares's son, Kyknos, "...beheaded strangers who came along in order to build a temple to Phobos (fear) from the skulls."