Missions give 40 CP, 3 Tier stones and 2-6 resources. This is true for missions at all continent tier levels (with the exception of some raw gems being given instead of resources).
At Tier I, one mission is sufficient to create one or two Tier 2 spells. The players get five missions before raising the CP, which is 15 Tier orbs and roughly ten Tier 2 spells.
On later CP levels, it takes more and more resources to gain new spells, while missions give the same amount. This forces the player to venture out and find secret missions or guardian powers to gather the needed resources. This is an interesting change, and makes the later Tier spells a challenge. But there is a large incentive to just do a single mission at a new Tier for the first 3 orbs, and then do secret missions until you can create new spells. May not be totally optimal, but it is what I have found myself doing.
This gives the players a nice pyramid of skills, with a large number of low Tier spells, but just a few high Tier ones, but still having 15 of each Tier orb. Most of these high level orbs go completely unused due to lack of resources, with the players just scared to do more missions because of CP. At CP level 5, however, CP gains stop mattering entirely. I routinely end up doing 20 or 30 missions at CP 5, just for fun and resources. This leaves me with more at-level spells than I know what to do with. The players get every spell.
What if the amount of Tier orbs and CP given by missions decreased as the CP level of the continent rises. At Tier 1, you still get the 3 orbs (or even more) and the 40 CP. Tier 2 may only give 30 progress. Tier 4 mission might only give 1 orb and 13.4 CP, letting the players complete 15 missions while not getting more than the total 15 Tier 4 orbs. Players could do more missions, which are fun! Maybe this could all be configurable like AIP over time is.
Tier 5 missions could also increase the CP. Maybe just by a small amount (maybe a huge amount - players should have already worried about creating their Tier 5 spells at CP level 4). Dungeons can already go way above Tier 5 monsters, maybe so could the continent. This would balance between players at a "fresh" Tier 4 and those who have completed two dozen missions and all the spells. The overlord isn't just going to sit there and watch. Could the players dig themselves in a hole? Maybe. Maybe they should be allowed to. It wouldn’t be inescapable like continent sinking was, because the amount of Tier 5 spells just keep increasing with resources.
This is probably a much larger change than there is time for by 1.0, but I believe (perhaps foolishly) that it would not be a large mechanical change.
AI War has a great difficulty curve across a single play-through, and it is something that did not just come about overnight
I remember the large push for an exciting end game.