Supergirl #21 Variant Edition

"Mourning the loss of the Kryptonians wiped out by Rogol Zaar, Supergirl decides to play detective and sets off into deep space to learn more about the would-be usurper. Using whatever tech she can scrounge, Supergirl builds a star cruiser, and after intel from Green Lantern, she blasts off into the cosmos with Rogol Zaar's deadly axe to solve the mystery-along with a traveling companion you won't believe! "