Swarming Square

The  is a sentry that mirrors the Swarming Sentry, but spawns tiny Square crashers that look similar to Summoner Squares instead of triangular ones. To further set it apart from Swarming Sentry, it autospins as it moves. All of these details together indicate that it may be intended to be a Sentry version of Summoner.

and it evolves into:Summoner Lite