After Marlith began her assault anew, the battle became a desperate frenzy for Rune and his companions. Their allies had been knocked away by the second wave of flame and rendered unconcious. Their sleeping bodies now littered the battlefield just a shirt distance away.
Rune did what he could and stretched his control over barrier magic as far as possible, creating a wall of safety around them. It was still hard for him to create complex structure. Making a sword might seem more difficult than adding a curve to a wall, but it couldn't be more far from the truth. At least in Rune's case.
Still, even that wouldn't last forever. Rune's barriers were only an imitation running on borrowed mana from his connection to Luna's fragment. Unless he fused with her, they would never match up to the real thing. Marilith's fire, however, was only growing stronger. It was the real thing--a flame from said to burned down an entire world. His barriers were pathetic in comparison.