That beastie is called the Mangog. The Mangog is very kind and friendly. It wants hugs.
The ads on the left page are truly special:
Scientific Wonder XRAY GLASSES. It can't be true, but look for yourself. Girls will never trust you with these, but let them look for themselves and apparently see legs right thru your pants. Amaze and embarrass everyone! Only .95.
CHAMELEON. Watch it change color! Wear it on your lapel! Alive! LIVE DELIVERY GUARANTEED. $1.95.
FAMOUS GERMAN MEDALS. Large, full size. Beautiful detail, authentic replica. Luftwaffe Nazi Pilot-Paratrooper $2.50. Nazi SS Swastika $2.50 Iron Cross $2.50.
MAMMOTH 9 FOOT HOT AIR BALLOON. AND 9-FOOT FLYING SAUCER. Ideal for July 4th celebrations, science clubs, or just real fun.
I can only imagine what the parents said when their son got a nine foot flying saucer in the mail.
Left page is a comic about Pete Duncan the Highschool Dropout and the importance of getting a GED. Great stuff!
Right page: Thor visits a hospital to heal Sif with his hammer's "strange rays." Apparently Mjolnir can create trans-dimensional vortexes, because Thor zaps himself and Sif to the Rainbow Bridge. Sif is no longer in her hospital gown, but wearing the latest in miniskirt armor.
Meanwhile, Loki has staged his weekly takeover of Asgard.
Left page: Fandral, Hogun, and Volstagg are smashing things because they're bored. Right page: Loki shows up and asks (very reasonably) that they stop vandalizing the palace. Or, as the writer puts it:
But suddenly, the shrill, piercing, raucous voice of Loki rents the air like a banshee's wail--!
"DESIST! THY LIEGE COMMANDS."
Mythology 101: Loki is known to the Norse as the Silvertongue. His words can charm the birds out of the trees and soothe a savage Thor. It's probably a safe bet that he was never imagined as having a shrill voice.
Anyway, Loki sends Fandral, Hogun, and Volstagg off to fight the Mangog.
Thor and Sif arrive at the palace. He and Loki turn on Yon Mystic Visi-Crystal (THAT'S REALLY WHAT IT'S CALLED) and watch the Mangog stomping his way towards Asgard in search of hugs.
And that's it. There are a few more pages, but the issue ends before Thor ever reaches the Mangog. So I have no idea how that fight ended. It's a safe bet that Thor won.