This is a Dungeons & Dragons roleplaying adventure featured in the Animated Series Handbook that came with the BCI Eclipse DVD box set. The maps used are from the Fantastic Locations: The Frostfell Rift module.
Beneath The Blade Of Sword Mountain is a prequel to the Dragon's Graveyard episode with the heroes battling against the frost giant named Yragmul to find the portal home hidden in the glacier that Dungeon Master instructed them to find with his "fire in the ice" riddle.
The heroes must navigate Sword Mountain to reach one of the Great Glaciers on the other side in time to witness the fire in the ice phenomenon that will reveal a portal home. To do so they must venture through the subterranean kingdom of the frost dwarves whose halls and tunnels are carved throughout the mountain, and may be aided by a frost dwarf named Dorrin.
The evil frost dwarves were ruled by king Ulfgor Frostborn and queen Auldhild Frostborn who formed an alliance with Venger. Venger betrayed the king and queen by sending Yragmul to capture them, then imprisoned them in columns of ice with illusions to make them look like demons. Yragmul then broke king Ulfgor Frostborn's crown in half which transformed the frost dwarves into normal dwarves; demoralising them and making it easy for Venger's minions to enslave them.
The two crown halves are worn by Dur & Joss, a two-headed slaver ettin who wears one half on each of his heads. If Dur & Joss is defeated and the two halves of the crown joined it will become magically mended and release the king and queen, whose return will restore the frost dwarves. The grateful king and queen will be repentant and renounce evil.
Having battled orcs, ice mephits, a displacer beast, a wyvern and a harpy the heroes will finally confront Yrgamul outside on one of the Great Glaciers where the Dragon's Graveyard episode begins.