Damien dragged Lunaria through the underground as fast as he could, but it wasn't an easy thing.
In the first place, the tunnel system was far too complicated. Even if he wanted to just teleport straight down continuously, it was impossible.
His awareness was concentrated below him as far as he could reach, scanning the area. If he could, he would directly teleport to a tunnel in that area. But most of the time, there simply wasn't one there.
He had to rush through the tunnel system on foot and search for viable locations to teleport to, while also keeping the location of the Primordial Undying Tree in mind so he didn't stray too far away.
He couldn't even use the maximum range of his teleportation, since long-distance spatial travel would negatively impact those without an affinity for it. He needed Lunaria to stay in peak shape for the upcoming struggle.