In Highmountain, I would have a Rivermane Shaman or Brul fists popping out of the ground.
In Stormheim I would get a Rune of Valo(u)r or a Val'kyr come swooping down and flying off again.
In Surumar I'd have withered come running through like a stampede or Nightborn helpers.
And in Azsuna I'd have a bunch of Azure whelplings come swooping in and attacking my targets.
I know that all these helpers actually are helpers from various quests in that zone which may or may not be up, but why are they around when I am not doing that particular world quest? HK theorised that it was from handing in your bonus cache from each 10k bonus rep you get with the factions. I have no idea if that is true or not. Maybe someone out there can tell me the answer! I've seen other people with the same mobs helping them too, so it's not just because I'm lucky.