The Raid's Discovery mode allows you to find players, get familiar with the content (and your team)) and basically do a lower stakes test run of the Raid. If you and your team vibe well and breeze through it on golden wings, well it seems that you've found yourself a solid team to take on the Raid proper.
But yes, the PTS is a test server and is subject to change as we move forward and take in player feedback. So please continue to share that feedback with us here and on the PTS forums.
But yes, the PTS is a test server and is subject to change as we move forward and take in player feedback. So please continue to share that feedback with us here and on the PTS forums.