You’ll first encounter Guardian Arkveld in Chapter 3, during “The Faithful Keepers” main mission. The definitive fight won’t take place until the “Broken Chains” mission. As such, all you need to do to unlock the monster is progress through the main questline.

Guardian Arkveld is the primary target of the Guild's investigations in the Forbidden Land in Monster Hunter Wilds. After tracking it through the region's various biomes, you've finally found the artificial monster deep in the Ruins of Wyveria.

The flagship monster of Monster Hunter Wilds is Guardian Arkveld, the White Wraith, a violent foe whose long-reaching limbs make them hard to beat.