When fighting, you'll find a new kind of boss. To defeat them you'll need to destroy boxes in order (eg. Task: Destroy the blue boxes), with some other enemies to fight. Then you teleport to the boss with your teammates but instead get teleported to an unofficial part of Bergen Trail where Direct Links are disabled.
When you find your way to a large flat land, you'll meet the mysterious Blue Avatar from the M.S. Solar, then you'll be forced to fight him. This is a difficult fight without preparation, so you may need to stock up on consumables before beginning the Raid. The first duel against the Designer takes place after Lea is forcibly teleported out of the First Scholars raid, into an unofficial part of Bergen Trail.
At first, the Designer does not attack, but he will teleport to dodge all of Lea's attacks. After dodging a number of times, he will start attacking and Lea will be able to damage the boss.
The Designer surrounds himself with colored orbs of which he can throw at Lea to perform elemental attacks: heat-, cold-, shock-, or wave-based. He can also charge at her, dealing neutral damage on contact. As the fight progresses, he will charge up to three times in succession and use additional attacks that lack element properties.
Every time Lea depletes a sixteenth of his total HP, the Designer smashes the ground three times, twice beneath her and a third time to destroy part of the arena. His behavior then changes.
He generates a heat/cold shield that reduces damage taken to zero from attacks that are not cold-/heat-based. When the Designer is hit into a break state, this shield is disabled.
At 11/16 HP, Sergey will open an exit point for Lea to escape. However, the Designer quickly notices this and blocks Lea right before she can get away. He then proceeds to endlessly charge at her until he lands one last hit. He inevitably captures Lea, sending her to the Vermillion Wasteland.