Easy enough, tell what mid-raid or raids you think WoD should have had before finishing up with HFC. Bosses from HFC are up for plunder, you don't need to design the encounters but do need to come up with at least a little bit of lore.

The Defense of Shattrath, a hard 3 front battle against the Iron Horde, The Legion and Guldan's Shadow Council Cultists:

Boss 1: The Iron Fleet; a sea battle where you need to go out among the wreckage of the first Iron Fleet to reach and sink a command ship. Not a vehicle fight as such but as you take over Iron Horde vessels you are able to open fire from them onto the command ship as well as the next ship in the fleet.

Boss 2 and 3: The Legion will not be stopped; Khadgar teleports you to an entrance where you face waves of demons - reminiscent of old Mount Hyjal - culminating in a fight versus a Pit Lord and then an Eredar General.

Boss 4: Shadow Council Priestess; You are sent beneath the city where you find the Shadow Council and their demonic allies are hard at work raiding the catacombs of Archinduon. Exarch Maladar charges in to stop the desecration and as you go to follow your way is blocked by a Shadow Council Priestess that bars the doors with shadow magic and you have to defeat to get by.

Boss 5: Gorefiend Lives; You defeat the priestess but arrive in the next chamber too late and watch as Guldan traps Maladar, kills him and implants within him the soul of Teron'gor. Right before his death Maladar empowers you and your allies with ancestral draeneic buffs giving you the strength to beat him.

Boss 6: The Warsong Outriders; Khadgar again teleports you to another entrance of Shattrath where the Iron Horde under the strength of the Warsong Cavalry has broken in. Defeat the Iron Horde and the Warsong, eventually culminating in a council fight against champions of the Warsong and Burning Blade.

Boss 7: The Infernal; Guldan seizes on the opportunity given by the Iron Horde and sends in a giant infernal that breaks open the door to the inner sanctum of the city. By attacking various parts you can lower the combat proficiency of the demon but in order to finally stop it you have to give a K'Uuru or some other Naaru time to power up and defeat it. Standard gauntlet type fight with a lot of adds and AoE damage.

Boss 8: Hellscream; Gromm finally arrives and strikes down the Naaru that defeated the infernal. Then begins a fight with you. A lot of adds to deal with again from each section of the Iron Horde - assassins come in stealthed, Deadeye clansmen throw spears from afar, Blackrock grenadiers, warsong outriders and their wolves, thunderwhosawhatsits release various beasts that you have to deal with. Shadowmoon has healers that will actually shield Hellscream as well as heal him and absorb energy from the fallen naaru attempting to turn it into a voidlord. Mythic version includes the fall of Hellscream where at 30% Guldan shows up and offers the blood of mannaroth to Gromm which results in him going green, berserk and places a pool of felblood on the floor like the kilrogg encounter where enemies can buff themselves and add fel damage to their abilities.

OK, let's see what all you guys have!