Not sure if you're seeing some out-of-date text, something that needs to be cleaned up... but, there are no more "featured" raids since Edge of Fate released. Raids no longer give "pinnacle" gear. All the raid loot is currently outdated, till they update it to the tiered system (in June). You can play any LEGACY raid, at any time, on any difficulty (Master or Normal)... and farm repeatedly for the exotic to drop. * Desert Perpetual is a new raid (post-EoF) and works differently. There's no Master mode, you must add various "feats" to increase the difficulty & get higher tiered gear to drop. You have a chance at the exotic only once per character each week.

All raids and dungeons (except for the newest ones) are all open now to farm. All challenges are available and the exotics can be farmed. This was announced a long time ago and has been like this since post EoF.