V.V.V.V.V. said:
Deathcore is a pretty new genre, but I wouldn't necessarily call it accepted yet (generally). It usually requires two parts metalcore and one and a half parts (brutal) death metal/deathgrind.
Despised Icon
Animosity
Happy Face (seriously, they're good)
Zubrowska
All Shall Perish
etc.
All of that is commonly accepted as "deathcore." However, like "viking metal" (which I am vehemently against the usage of as a genre), it's not a real genre.
Despised Icon's The Healing Process is a fucking brilliant CD, so I highly recommend it as a starting point if you want to hear GOOD metalcore (NOT As I Bullet For My Dying Trivium gay shit) crossed with GOOD deathgrind.