Journey into Mystery / Thor Vol 1 #257

Plot

As the heroes seek Sporr, Relstor tells the Asgardians the history of Levianon; They finally come across one of Sporr's tentacles, only to have it collapse the hallway again; Back in Asgard, Balder and Karnilla look upon a mysterious army that has appeared on the outskirts of Asgard; Back on Levianon, Thor holds up the ceiling to save everyone; They then manage to track down the monstrous Sporr; The Asgardians battle against it, but it takes Thor to bring it down; But before he can stop them, the men of Levianon kill Sporr while it is knocked out. (mycomicshop.com)