The Castle under the Frozen Sea debuted only once in the pages of Champions Champions #3 by Eclipse Comics and published October 1986.
The evil organization named DEMON steals the magical Hellfire Crown from the team of heroes known as the Champions. Soon a race begins for both groups as they attempt to retrieve the jewels known as the “soul shards”.
One of the Champions eldest members the man named Doctor Arcane is well aware that the real owner of the soul shards is on the verge of awakening, and if she does her vengeance would unequaled by DEMONS own schemes for the power of gems.
An astrally projected Doctor Arcane speeds into the wilds of northern Canada, followed by Icestar. The two reach the area in which Doctor Arcane states that they must stop, however Icestar is confused and unconvinced since nothing is near by miles. The Doctor magically parts the water and Icestar freezes it so they can get in, and they come across the slumbering body of Melissa D’Arque.
As the Doctor begins to tell the past tale of when he and the original Giant captured Malice before, they took the three soul shards to leave her lifeless like and powerless. However to his dread they had not hidden them well enough and DEMON agents found them and obtained the knowledge to combine them with the Hellfire Crown.
After they get the soul shard and get out, the Castle under the Frozen Sea collapses into nothingness. The Castle in fact was never truly there, apparently, and the only reason Icestar could see it was because he was with Dr. Arcane. So only wizards could find the place. People who could probably pull the same possession trick he used.