on Monday, reminding fans that even the God of Thunder questions his purpose from time to time.«My superhero-ing days are over,» Chris Hemsworth's Avenger declares in the new preview, as fans see him bidding farewell to the Guardians of the Galaxy and embarking on a journey of self-discovery. «I need to figure out exactly who I am.»But what if there is another warrior who could prove just as mighty? Perhaps even… mightier?The final seconds of the clip preview a reveal nearly three years in the making as Natalie Portman returns, reprising her role as Jane Foster and wielding Thor's hammer, Mjolnir, as the comic-canon variation, Mighty Thor.Watch the full teaser for directed by Taika Waititi , below:Hemsworth also shared the trailer on his Instagram page, writing that has «all the feels of a classic Thor adventure.