This is my AtS counterpart to project-ethea/Invasion_from_the_Unknown#93. This one comes from cooljeanius/wesnoth_mods#3 and is meant to close it. This one is somewhat simpler than the IftU one, since there are no map changes, and no new units added here. It's mostly gold/income/turns tweaks, although there are a few other changes besides those to note:
In E2S05 there are several:

• I buff Anya's HP a bit, since she's rather fragile.
• The additional dialogue about the windmills is to guide player exploration, to ensure they don't waste time trying to capture them.
• The reduction of Unidë's moves is to prevent her from leaving her keep to capture a village on the first few turns.
• The southeast elves are now more likely to recruit Shaxthals, which is meant to address issue E2S05, The Eastern Front: Shaxthals referred to even if none have been recruited yet #97 (I can't guarantee that it fixes it entirely, though)
• I added some findable Aragwaithi units in some villages, for reasons mentioned in some comments I added to the scenario file. They still need dialogue written for them, though...

Some other things to note:

• In E2S08, the increase in recruitment diversity/randomness to that one side is because on my first playthru it recruited pretty much all just Chaos Raiders, which was boring. I was considering having the values be regenerated every turn, to make things more chaotic (since they are the CHAOS Empire after all), but instead opened Allow the {RANDOM} macro to be used inline to set values wesnoth/wesnoth#6319 because of this (I still might try ProditorMagnus's suggestion from it, though)
• E3S07A was a bit harder to modify since the usual gold/income tweaks wouldn't work, so instead I modified the units placed on-map. The differing traits on Easy were chosen specifically so that they wouldn't be the opposite of their positive traits on the harder difficulties (e.g., don't give a unit Weak that gets Strong on the harder difficulties). The infliction of the "slowed" status effect might need some in-universe justification written for it, but in gameplay terms, I found it to be the most effective way I could think of to stop the enemies from killing me.

...and... that's about it!