Answer:
Thirty white horses on a red hill, First they champ, Then they stamp, Then they stand still.
I turn around once. What is out will not get in. I turn around again. What is in will not get out.
Flat as a leaf, round as a ring. Has two eyes, can't see a thing.
I can be short and sometimes hot. When displayed, I rarely impress.
My first is a creature whose breeding is unclear. My second, a price you must pay. My whole can be found in the river of Time and refers to events of today.
Do what he says and you'll be fine, don't and you lose the game.