Evan came before the barrier and looked at it carefully.
He didn't waste his mana by attacking the barrier, because he already saw even Kevin and others were not able to do anything to this barrier.
After looking at the barrier for some time Evan sat down near it to recover the mana that he used earlier while using his shadow walk skill.
Even though he still had more than 70% of his mana remaining, he first decided to recover it before going through the barrier.
He wasn't worried about the barrier because of his shadow walk skill. He can pass through it by using his skill.
When he was trapped by the bandits in a barrier during the mission, he used shadow walk skill to escape from that barrier.
At that time he noticed that passing through the barrier increase the mana cost by quite a bit.
He wasn't sure about the level of the barrier in front of him so he first decided to recover all of his mana, before passing through it.