Back when I first demoed ARR, I was in love with what XIV 1.0 became Then a FATE spawned, and it was such fun because I thought it was a random occurrence like rifts in the RIFT game, and was sorely disappointed to find out they were fixed in content and location.

I would like to suggest Spontaneous Active Time Events, or SATEs. These would be in a random location on the map, and could be a random level, possibly 10 levels above the highest mob of the zone.