Battle of Helm's Deep

At the beginning of each player's end step, if that player controls creatures with total converted
mana cost 8 or greater, exile Battle of Helm's
Deep. If you do, that player draws a card for each creature he or she controls.
"It is said that the Hornburg has never fallen to assault. But now my heart is doubtful. The world changes, and all that once was strong now proves unsure. How shall any tower withstand such numbers and such reckless hate? " Theoden