Attumen the Huntsman

You can Find all here http://www.wowwiki.com/Attumen_the_Huntsman

Step 1 :
Tank pull midnight , dps him until 95%

Step 2:
At 95% Attunement spown, quick off tank him away from Main Tank and others party members ( his cleave hit hard ).
Continue Dps on midnight until 25%

Step 3:
At 25% Attumen will mount and aggro will be wiped.
Let tank get aggro then dps him .The only difference after mounting is the additional charge ability.
When you have too much aggro, he will charge you for a huge ammount of dmg.

Remember Horses start respawn in 30 minutes, so boss must be killed before.

From what i heared u can Disarm Attumen.. will save alot of dps and healing .