Trivium's Matt Heafy and Linkin Park's Mike Shinoda announced way back in January that they would work together on a new song via their Twitch channels.
The song is called "In Defiance" and you can stream it in full below. It certainly doesn't sound like anything either of the two would've come up with alone, which is awesome and kinda the whole point of collaborating.
The artwork for "In Defiance" was created by Half Sumo.