Attumen the Huntsman (patch 2.4.2)

This is the first boss in Karazhan.

First Phase - The first phase of the fight is just Midnight the horse. Midnight does not do any AoE or anything special really so just heal the tank. Searing totem is recommended because once Midnight is at 95%, Attumen will spawn and runs into the middle of the raid group, and the searing totem will usually get picked up by Attumen so that gives a 2nd tank (usually the Main Tank) time to pick Attumen up.

Second Phase - Attumen does a nasty cleave so stay away from him. The only people that need heals are the two tanks, unless some other players stand in front of Attumen. When Attumen or Midnight's health is down to 25%, Attumen will mount Midnight. Aggro resets when they mount, but good tanks can easily pick that up.

Third Phase - Stand directly behind Midnight's butt to prevent charges. The charge does a lot of damage. I'm not 100% sure but I think the boss charges the person who is furthest away from the raid group, which is usually the hunter if you have a hunter in the group. Use bloodlust and searing/fire elemental totem to help speed up the fight. Again, the boss will cleave so please make sure you are behind him. Just keep the main tank and anyone who gets charged top off in heals (and anyone who gets cleaved =/). The end.