Answer:
The line a runner strives to reach
The eight of us go forth not back to protect our king from a foe's attack. What are we?
The day is their night and the night is their day, when I shout and they shout back I run away.
Lovely and round, I shine with pale light, Grown in the darkness, a ladyβs delight.
If you have me, you want to tell me. If you tell me, you don't have me.
I am the fountain from which no one can drink. For many I am considered a necessary link. Like gold to all I am sought for, but my continued death brings wealth for all to want more.