Trance Metal is a mixed Genre of Melodic Death Metal and with Trance music incorporated in it. It is a "metal" genre and doesn't consist of post-hardcore/electronic bands like Enter Shikari (they have trance elements but are not "trance metal" or other "core" bands like Attack! Attack! (synthpop-core not even trance).
Trance Metal usually are heavily guitar riff influenced bands (like most melodeath bands) with little breakdowns grooves or none at all. They are heavily influenced by bands like In Flames, At The Gates, Children Of Bodom, and/or Dark Tranquillity.
"During the mid to late 2000s, certain melodic death metal bands, such as Blood Stain Child, Timecry, Silent Descent, Lost Eden, The Dawn Chose Orion, and Deadlock, began to incorporate techno or trance beats and atmospheres into their music. This relatively young style has been tentatively referred to as trance metal." - wikipedia.com
random dude 1
"hey dude have you ever heard of those bands Silent Descent, Blood stain Child, or The Dawn Chose Orion???
random dude 2
"yeah man, thats an epic genre called Trance Metal!"