The Ranger could quite clearly see the monster stop...apparently aware of his presence...and wait, evidently planning on letting the Ranger come to him. A clever action, considering the circumstances...and the elf doubted that the creature would have done the same if he was not utterly aware of Cruallassar's actions. It had already shown itself as having an uncanny awareness of its surroundings before, without apparently the need for sight considering that its eyes were practically nonexistant. Some kind of ethereal sense like his own? Sonar, like the bats it seemed to somewhat reassemble? Probably not a ground vibration sense, considering it was equally aware of himself and arrows in flight as on the ground, or if it did then it wasn't it's only asset. It had no magical aspect to its aura, so nothing in that way.

Whatever it's senses, it was obviously willing to wait for the time being. Normally, Cruallassar would do the same...he was in better shape than his opponent, the wound to his eyes notwithstanding, and could probably wait longer. But the creature was not trapped, and could easily escape, and the part of the tunnel he was blocking was not a seemingly vital part of the underground network. Cruallassar himself could engage the creature in any tunnel it fled to...but trying to ambush him anywhere was a likely losing proposition. Much better to strengthen his web now, while the creature was halted. He shifts into ethereal shadows, diving through the rock and emerging into the tunnel leading from the monster to the surface, and fires two more of his net-trap arrows, erecting a similar web to the one he already left behind, before repeating the process.