Barrow slowly replaces the environment around himself with an otherworldly forest. He cannot move beyond the effect of his power, but he can extend its radius by standing at the perimeter of it. After he leaves the area reverts to normal.
Has some extra senses as he started to move towards the Brockton Bay Portal well before it was made public.
When Taylor Hebert finished with the folder about the Adepts, she moved on to the file about the Lost Garden and Barrow. Tattletale's notes in the file suggested that he was moving towards Brockton Bay and had since the conclusion of the fight against an S-Class threat.
He later sent people after the Undersiders while also having them clear a path for him. 
↑ 1.01.1Barrow Slowly replaces environment within a fair radius with an otherworldly forest. Cannot move beyond forest effect, but can extend radius by standing at perimeter. Lost Garden Shaker Wildbow's Parahuman List
↑ 3.03.1I put the folder away carefully, picked out another. Lost Garden. High threat level, low crime rate, low engagement level and moderate activity level. Leader, Barrow. A powerful shaker, similar to Labyrinth, only rather more single-minded in what he did. He couldn’t leave the altered area he created around him, only extending it slowly to an area while letting it fade behind him, an effect described as ‘a depression’ with overgrowth extending into the surrounding neighborhood. Tattletale’s own notes in the file suggested he was making slow but steady progress towards Brockton Bay, and that he had been since the portal appeared.
I flipped through the rest of the file. What kind of people gravitated towards someone like that? Apparently a lot of very young parahumans, boys and girls around Aisha’s age, had gathered around the middle-aged Barrow. A little creepy, when I imagined that collection of capes and the resulting dynamic. -
Excerpt from Imago 21.7
↑Lost Garden approacheth, sending members after us and trying to clear way for Barrow to advance. Annoying but no problem until they enter city limits. - Excerpt from Drone 23.3