24. By the evening of Brainiac's arrival, many of Superman's friends and allies arrive in the arctic, attempting to assist him, but they are unable to do so. What stops them?
From Quiz "Whatever Happened to the Man of Tomorrow?" Part 2
Answer:
An impenetrable force-field erected by Brainiac
Many well-known superheroes make cameo appearances, including Batman and Robin, Wonder Woman, and Captain Marvel, but none of them can break through Brainiac's force-field that completely surrounds Superman's fortress. Brainiac and his allies begin attacking Superman's fortress with weapons from Brainiac's ship. Superman destroys most of these from long range with his heat vision. However, when he and his faithful companion Krypto the Superdog attempt a more direct counter-attack, they are driven away by the Kryptonite Man, whose powers seem to have mysteriously increased tenfold.