Blizzard has published new information regarding this week's PTR raid testing schedule, which will run over two days and test 4 new bosses, including the much anticipated Anduin encounter.
Halondrus the Reclaimer and Prototype Pantheon Heroic encounters will be tested on Thursday the 16th of December at 14:00 PST (17:00 EST, 23:00 CET).
Anduin Wrynn and Vigilant Guardian Heroic encounters will be tested on Friday the 17th of December at 14:00 PST (17:00 EST, 23:00 CET).
Blizzard previously mentioned that they may not test the final bosses of the Sepulcher of the First Ones, and because Anduin was described as the "final" boss of the first part of the raid he might not get tested on the PTR, however now we know they were referring to the final three encounters.
Third Round Of Raid Testing Schedule For This Week Including Testing Of The Anduin Encounter
After this test ends, players would have seen the first 8 bosses from the Sepulcher of the First Ones, which have all been tested before the holiday season begins.
We can assume this is the last week of raid testing for a few weeks, and Blizzard will evaluate all their data and decide if they want to test the remaining three bosses or save them for the live release.
There is a chance only the Jailer, the final boss does not see raid testing which is still a good experience for Blizzard to try out, and gauge the community reaction to holding back on testing final bosses for hiding lore and making progression more interesting for the first guilds to clear the raid.