Tunnel

The reason Aru had to rank up was to gain the ability to use the wood element.

His idea was to use the wood element to manipulate the trees to grow roots deeper and thus increase his sensing range underground.

Although it was just an idea at the time, its feasibility was soon proven by how wildly the shrub changed under his control.

'If the shrub can change shape and size when I inject it with enough spirit energy, there is no reason I couldn't do the same with trees.'

'First, let's try it.'

He sat down, closed his eyes, and sensed the linked trees nearby.

In the darkness of his consciousness, they began to appear like beacons of light all around him. The closer they were, the clearer he could sense them.

'Normally, I receive energy from the link network through the system. However, this time, I have to actively control and send the wood elemental energy to the tree I desire.'