Fortunately Dave was really stupid and ignored reality and walked over the river of lava. The real reason for the success of this stupendous task were actually a few rock piles, that were protruding from the lava. Having passed the lava river Dave got really hungry and confused the torch with flaming shashlik and wanted to eat it. Before doing so a smarter* Rock Raider snatched the torch from Dave's hand while shouting "No! The fate of the world depends on it!". While Dave tried to satisfy his hunger with the next best thing - a piece of ore - the smarter Rock Raider, who was actually Power Miner No. 471, couldn't continue the path of destiny due to a minor inconvenience: a group of bootleg LEGO bandits.
*which isn't an amazing feat