"Joining the Fray
Challengers can test their mettle against the Velkk by examining the Weathered Canvas in Marjami Ravine (I-11) once all party and alliance members possess velkk fetishes. These fetishes can be procured from the corpses of Velkk skulking about the ravine......"

Like the title says.

And yeah, this is finally content that will have your fingers hurting. Its pretty unforgiving. No sneaking around in there like we do in delve, you are going to have to truly fight your way through the map.. Best thing since dyna pre-cap-raise.