Answer:
Do what he says and you'll be fine, don't and you lose the game.
I'm not man's best friend, I'm their enemy, I can mark your end, yet you do not see me, I am very small, but very tough, If you have me, then you have it rough.
There are 30 cows and 28 chickens. How many didn't?
As a whole, I am both safe and secure. Behead me, I become a place of meeting. Behead me again, I am the partner of ready. Restore me, I become the domain of beasts.
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.
Keep doing me to avoid lens dryness