Beings of Tash Kalar
The Herald uses the same idea as the military leaders: He stands (diagonally) in a small group of pieces, which resembles a crowd rather than a military formation.
The Herald asks the pieces to rearrange. It is the weakest move type, as the rearranging is just ceremonial. No stomping on the weaker ones, please.
The Herald is a bit more difficult to summon than the Messenger, but he allows you to do lots of movements with various pieces. Many tasks can be fulfilled using him (especially the ones that require summoning two beings – if you summon the Herald with your first action, you probably find a way to rearrange your pieces for the second summoning). He does not allow you to destroy, but he can still be useful in a deathmatch: You may use him to set up a pattern for a deadly legend or another strong being.
Originally the Herald allowed you to "choose a direction, perform a standard move with up to three of your pieces in that direction". It was much harder to see the options, and the use was relatively limited. I didn't want a card that complicated in the Imperial decks, so the conditions were loosened (but the moves weakened). The original effect of the Herald then inspired the effect of the Centaur Chieftain card.