My cousin and I defeated Malistare and we unlocked Celestia. And so did my friend faught Malistare, his Wizard is named Eric Hawkstrider. I have two questions: how come my cousin and i unlocked Celestia but my friends didn't (he defeated Malistare with me), And General Stormclaw is basically impossible even if we defeat him. Estrakir is for sure going to be Impossible.
Young Wizard, there's no need to post this repeatedly.
Your friend is not yet high enough level to enter Celestia.
Only players who have reached level 48 and completed the Dragonspyre quest "The Final Countdown" should speak to Merle Ambrose for more information about Celestia.