After observing the horrid nightmare for almost an hour, Arad managed to learn a few things. While it's near-immortal, all the small ones do is eat at the insides of its stomach, not the upper chest or head.
The plan had now become clear. He and Neige need to make a sneak attack at the start of the fight and make sure to drop the boss on its head to deal maximum damage from the start. They can then hide back into the shadows and sneak attack it again.
Arad returned to their hideout and found Neige sitting beside the fire, hugging her knees with a terrified and pale face. Her eyes reeked with madness, glaring straight at the flames without even blinking.
"Our plan still stands. I cut its wings, you knock it down." He approached and took a closer look at her face. "You look worse than before."
She remained silent for a while, then slowly turned toward him, "You didn't see what I saw."