@ranger- apherium has a certain "stat", just like if you were hitting a real target. For example, lets say apherium is 2mil comb stats. If I am 1 mil comb and hit apherium, (is it apheriun?), then I will get a boost to my plunder because of the relative strength of my target. However, my plunder is capped due to my buildings and size.
Now, when I upgrade to be 3 mil comb, I become stronger than apherium. When I attack a weaker target, I make less plunder. It's always been like this.
I suggest we all send feedback requesting apherium pot up so we can make better gold off of him, but that's a whole nother (sp? Hmm. It's early) can of worms.