The new continent progression.

[paul1290]

From the official forums regarding the latest update:

Originally Posted by x4000

Essentially, what we've done is removed "Civilization Progress (CP)," and instead made it so that you kill lieutenants in order to increase the continent tier. In short, we took out one mechanic that was a bit superfluous and complicating things needlessly, and are now making better use of a more interesting mechanic (lieutenants) to accomplish the same thing.

Another way to look at this is focused around missions themselves: you no longer have to worry about world map missions accidentally making the world arbitrarily harder (through CP) by completing too many of them. And the secret missions are no longer so grindy by giving you fewer rewards than the world map missions -- both kinds of missions now give you the same, higher, resource rewards.

Yet a third way of looking at this is in terms of overall game structure: previously you would bounce back and forth between missions and free exploration, then eventually kill all the lieutenants and the overlord pretty much in one long string. Now you bounce back and forth between missions and free exploration for as long as you like, then take on the lieutenant of your choice, then keep improving your stuff until you are ready to take down the overlord. Much better flow, that.

[Lokarin]

What happens if you split up and kill multiple Lieutenants simultaneously?

[tigersfan]

Originally Posted by Lokarin

What happens if you split up and kill multiple Lieutenants simultaneously?

Then you would jump up two Tiers quite quickly. This would mean that you would have to buy diluter enchants to get the orbs you need to properly upgrade your spells for the future.