A Tribute to Immortality

When you complete this, the Crusader's White Warhorse is mailed to you along with the following message:

Dear[Player],

Tales of your recent performance in
the Trial of the Grand Crusader will be
told, and retold, for ages to come. As
the Argent Crusade issued its call for
the greatest champions of Azeroth to
test their mettle in the crucible of the
Coliseum. I hoped against hope that
beacons of light such as you and your
companions might emerge from the
fray.

We will need you direly in the coming
battle against the Lich King. But on
this day, rejoice and celebrate your
glorious accomplishment, and accept
this gift of one of our very finest
warhorses. When the Scourge see its
banner looming on the horizon, hero,
their end shall be nigh!

Yours with Honor,
Tirion Fordring

Feel free to look at the screen shot and correct any typos I made above.

edit: took out screenshot link

Since you apparently get 50 attempts at the start, mentioning them in this achievement is pretty moot, as you cannot die anyway, and probably can't reset bosses, so you have to do all of the bosses in the first attempt anyway - of course, with no one dying.

Keep in mind that this is also Heroic difficulty.