I'm a relatively new player, but I've been playing at least an hour a day since the start of the month. Right now, I'm trying out different mixes of elements, and I'm working on Frost.
I noticed that sometimes my units will start to heal during a match, when I don't have anything that should be providing healing. I figured it out, though. The Construction Hut has an aura around it that heals units. It doesn't heal structures, just units. The key thing though, is that there's nothing on its card that would suggest it has any healing for anything.
The Construction Hut has the ability "Maintainance" that says "Friendly buildings in a 25m radius will be constructed 45% faster and will require 25% less power cost"
It's supposed to make buildings construct faster, and doesn't say anything about healing units. Is this a bug? A discrete hidden feature?
I haven't put in a bug report since I'm so new I'm not 100% sure it's not supposed to be like this, plus it's not part of the purpose of the building, so I think it wouldn't be just an accident? But it does have a special effect so maybe? If you place the building, it has a glowing ring of blue light that shows the healing area.