Talk:FAQ/@comment-179.214.74.160-20160725043529/@comment-2605:A000:140C:8564:54B0:3096:21D1:A4F4-20171223210052

You must complete the game in normal mode (all the way to battleground), although successfully completing the Spirit Temple isn't required. Once you do that, say yes to the opportunity to play in Hardcore. After finishing the game, you can also go to the character area and change the difficulty to Hardcore. Once you are in Hardcore, you'll be able to complete all the stars.

Around the time you finish Hardcore, you should be able to enter the Astral Arena with much larger players, assuming your DPS is good enough.