Jack is beckoned into a a subterranean, volcanic labyrinth filled with traps by an echoing voice calling him to it. Following it takes him to a monster of lava who demands that Jack must fell him in battle or be slain, as the monster is a Viking warrior cursed by Aku to never ascend to Valhalla.
- And I Must Scream: After being defeated by Aku, the Viking was sealed in an unbreakable crystal and buried beneath a mountain. Akus plan was to leave him there forever, and although the Viking eventually learned to manipulate the rock around him to form himself a body, he remained trapped there, immobile, for centuries at least.
- Bittersweet Ending: The viking warrior's tale and circumstances are absolutely tragic and so many warriors met their end in the underground Death Course before Jack's arrival. However Jack was able to defeat him and break his curse. He was carried into Valhalla by the Valkyries and stands side-by-side the fallen warriors he lost to Aku centuries ago, reunited with his friends and family.
- Death Course: The lava monster set up an elaborate one that warriors have to pass through before facing him, including spike and arrow traps, collapsing ceilings and lava pits. Jack is the first one to have made it through.
- Death Seeker: The Lava Monster seeks a Worthy Opponent to defeat him in battle as his Curse Escape Clause so that he can die and join his loved ones in Valhalla.
- Greater-Scope Villain: Aku, for without him, the Lava Monster would never be.
- I Die Free: When Jack finally beats the Lava monster who is actually an imprisoned viking warrior that can only be released to Valhalla if he falls in honorable combat, the stone golem glows and shatters with the viking warrior crying out that the spell is finally broken.Lava Monster/Viking Warrior: Accursed monster! Your spell is finally Broken! I AM FREE!!
- No Immortal Inertia: After his curse is broken, the Viking regains the dashing mortal appearance he had as a human — and then promptly ages into an old, grey-haired man over a second or so as his immense age catches up with him.
- Rapid Aging: The Lava Monster becomes an old man and dies as time returns to him.
- Tragic Monster: The lava monster was once a warrior not unlike Jack, until one day Aku attacked his land. The man tried to fight back to no avail since nothing he had could harm Aku. As punishment, Aku encased the man in a crystal prison and forced him to watch as he destroyed his home and killed his loved ones. Aku then placed the man within a mountain, denying him a warrior's death.
- Valkyries: At the end of the episode, two descend carrying the Viking to Valhalla.
- Was Once a Man: The lava monster Jack fights was once an honorable Viking warrior, before being cursed by Aku.