I generally try to go with lesser known bands for this article because I like to showcase the guys who aren't getting the attention they deserve. I Killed Everyone isn't the smallest band ever (they've got a solid number of likes on Facebook at 53k with a nice fanbase) but they aren't on the same level as Whitechapel, The Acacia Strain, and Chelsea Grin in terms of prominence.
Anyhow, the ultimate point is that this band is one you should be listening to actively. They've got two releases under their belt Dead Peasants, and Necrospire, both of which are great albums with an excellent grasp on the characteristics of Deathcore. I'm not sure I'd label them a full on tech deathcore band but they definitely infuse technical death metal into their sound often.
Check out the song 'Dead Peasants':
Necrospire came out back in July and is one of the stronger deathcore releases this year. Well worth your time!
Buy their album!