With each new expansion you add to the game, you add about 4 regular cards to the Overlord deck. This both dilutes the deck by adding weaker cards in, and also makes it take that many more cards to cycle the deck. Is there any option, like possibly taking out an equal number of older cards, or increasing threat, to compensate the OL for this?
Otherwise, the more expansions you add, the <slight> more disadvantage the OL gets as his base deck gets thicker. Sure he gets access to more diverse monsters, but that doesnt really help.
Or can an Overlord opt not to include some of the new cards, just cuz he doesnt want them?
Eventually, once we add the 10th expansion, we will have added 40 cards, and doubled the overlord deck!