Beings of Tash Kalar
The pattern calls to mind a message passed from one piece to another.
After the message is delivered, one piece is ordered to move. I was thinking about strengthening the theme by requiring the moved piece to be adjacent to the messenger, but then it would be too weak.
The Messenger is a very useful being, especially in the High Form. She is priceless when there are summoning tasks (you can easily summon her on various places, and she allows you to set up a pattern for a second summoning) and also very useful if you want to control colored squares with heroic pieces (a heroic piece can force its way there even through a common piece). In the right situation, a hero ordered to go through common pieces may destroy lots of them, so the Messenger is useful even in a deathmatch.
The Messenger is one of the oldest beings. The only change during development was that movement was originally limited to 3 moves. But it retains its pattern and other aspects (it was never allowed to move legends nor change direction of movement).
Also, during development, there was a prototype picture of a mounted messenger – but it didn't seem right: The being itself is rather weak; it is the message that's important.