Some enemies in Diablo III have a nearly-transparent, blueish dome/bubble around them; it's much larger than the Shielding bubble (with a radius maybe two or three times the height of your character), and it can pass through walls. The Keywardens have it, and I've also occasionally seen it on elite mobs. What does this dome do?
Here's an image from Diablo Wiki of a Keywarden with its bubble: