Hi I just started to use blockades as a way to get some extra income and was wondering if some people here can answer some questions I may have about it. What determines the output of a city you have blockaded? Is it the higher the havens level the more you will get or is it how advanced the mines and lumberyards are constructed IE the higher their level. Sometimes I find a haven that is abandoned and I block it and some will give me more or less than others. So I was wondering what kind of abandoned havens should I be looking for. High level abandoned havens or any level havens and hope that the resources are highly developed. That way I can get the most of it for my time. Thank you.

It's two things:

1. haven level, and
2. owner's (in)activity.

The formula for an active (up to 2 days inactivity) player is 100+5*level, with the max. being 400.

Like stated above its level and activity. Generally from what I noticed level 50s plus give closer to 400. But my best suggestion is learn how to raid to get the most out of them. Scout first of course. Havens that have more rum than gold or lumber will give a higher value of Rum than the other 2 resources.