Although we have no Dragons to command, we have learned that Grom Hellscream, leader of the Warsong clan, has been captured by the Laughing Skull and is being held prisoner. Free him and he will surely aid you in your battles.
Although the mission briefing states that the player is fighting against the Laughing Skull clan, the enemy units in-game are actually colored white and aligned with the Shattered Hand clan. This may have been an error on Blizzard's part as in the next mission, the player is tasked with rescuing warriors of the Shattered Hand clan from the enemy.
While Mogor doesn't exist as a hero unit, he is presumably the lone ogre near the Temple of the Damned, but this is unclear considering this particular unit isn't even an ogre mage.