I always thought that some of the strategic stuff from the beta should come back in some form or another. Perhaps this is a good way to do it, although it's not clear in what timeframe you're supposed to be battling the overlord strategically. For example, it'd be cool if the overlord sent over a fast scout to try find out where the settlement is, and your job is to kill the scout before he can get back to the overlord. You could have the lieutenants send scouts first perhaps. Anyway, what timeframe does that happen in? Is it a sudden call to action? Should it happen in mission time? Should the bad guys move in real time?
Perhaps the overlord and the lieutenants could do some actions in real time, per tier. The longer you wait in a specific tier without countering their actions, the more stuff they can do. But if you move into the next tier, they suffer a serious setback and can't accomplish everything they wanted to in that tier. So they keep doing bad things, one thing leading to the other: first they send scouts. Once they send scouts they send armies. They build encampments of armies. Then they assault the settlement. Eventually maybe they start building a dangerous magic artifact. You can fight all those things individually, but they'll become more and more common. You can also use guardian powers to slow them down. But the best thing you can do is move to the next tier. Yes, their armies are strengthened, but for some reason they're also really pushed back and their work is destroyed -- the tiers represent you working on something that will eventually defeat the bad guys.
Why is this so important? Because it counters the currently negative effect of doing missions. Missions advance tiers, which make the game harder. But they're supposed to be continent progress towards the good solution. This mechanism would also clarify the connection between mission time and realtime. And it appears that people really do want a more pressured component to this game -- one that raises the stakes for all your actions rather than giving infinite time to do everything. This has always been a sticking point: the game is about the end of the world and overthrowing a dangerous overlord, but the devs wanted to make it laid back and non-time-sensitive. Perhaps this is a good way of combining the two.
Regarding the calls themselves, I see 2 ways to do this. You could have an immediate call to action that opens up a warp to the location. But perhaps it's better to have a call that starts a specific mission on the map, like an assault of your settlement. You can go to do this mission at any time within reason ie. if you don't respond within a ridiculous amount of time, the event resolves itself, usually badly. Again, you could make most events (or perhaps a certain amount of them) go away just by advancing the tier.
