They're considered the pioneers of Deathcore? Well, they've the Metalcore breakdowns and death metal vocals. Something about it doesn't seem like they're Deathcore-y at all.
Antagony
Antagony is an American deathgrind and metalcore band from Oakland, California, formed in 1999 and disbanded in 2009. They are known for being the fathers of deathcore.[1] Antagony has released three albums, each on a different record label. Members of Antagony have gone on to form bands such as Oblivion, All Shall Perish, Suffokate, Oblige, and Hacksaw to the Throat.[2] Years active 1999–2009 i heard them on KFJC sounded like Pantera sideways