45 is the level if you open the dungeon for the dwarf artifacts, and 4 is on the map itself. I just finished this mission, and that's what happened to me. The map is actually quite easy. I have a Frieda who is a great fighter, with 17 attack and 21 defense. I also leveled up the "Impact" perk, which increases damage by 5% multiplied by morale. My morale is currently +3, which gives me a +15% damage bonus. Combined with the 15% attack bonus from the "Expert" skill, that's a 30% increase in melee damage.
No, it was for the artifacts. I specifically decided to sacrifice them to complete the quest, even though I was in the dungeon alone before the battle with the lava creatures, and there were 4 other units standing nearby.
I finished Frieda at level 27, but she's great.
