You can do NMs. These are similar to fate bosses and they scale with the amount of players there. They are spawned by killing a certain mob a lot of times. There is a eureka tracker that says which enemy to kill and where to spawn it, along with any weather or time conditions.

Eureka is fun, but it's not for everyone. It depends what sort of person you are. Personally, I really enjoy it, even just kill grinding.