A Dread Lord leads the assault, and this is the first time we get a look at his portrait. Behind him are three skeletons and a Necromancer. We note that the Necromancer no longer summons buildings, and hence it is now natural for him to be in an attack party rather than hang on around at main base.

The building in full view is a Troll Lodge, and half of a Troll Voodoo lunge is visible on the very top right. A Troll Witch Doctor is just visible, and it's unlikely he'll be able to do much against the attack.