Thunderbrd
C2C War Dog
If global effects would help, you could take a look at the tag in effect on the Mound wonders that makes all of the Tumulii pick up an adjusted output.I wa only thinking of construction costs. It is the only one that can be done so that it varies with or without slavery. The cost of one building can be affected by the existence of another. Unless I make a resource there is no way to adjust the value. There is no way to adjust maintenance costs at all as far as I can see.