Calldown:MULE is a formerly generic talent that repairs allied structures across the map, greatly reducing the impact of enemy pushes if they do not destroy a building. If left unhindered it can potentially bring a Fort, Keep, or the Core itself back to full health, being the only ability capable of doing so. It can be cast with Global range without the need of vision, and can be targeted by friendly abilities such as healing or Abathur's Symbiote, but it only has 140 (+43 per level) health and can be killed preventing it from repairing. It also only lasts 40 seconds so it has a max of 66% uptime. There have been complaints that the MULE is a Terran unit so it shouldn't be summoned by Abathur who is Zerg.
Heroes with MULE
Abathur is the only hero with this talent.
These heroes no longer have MULE as a talent option.