When using more than one expansion board, the modified number of players is one less for each additional board used. (In a 5-player game using KH and DH, the new modified number of players is 4.) The rules state that this handicap if for such things as monster limits and the number of gates that can open.
What about during the Final Battle? In a 5-player game using both KH and DH, does it take 5 hits or 4 hits to remove a doom token.
My guess would be that the Final Battle is unchanged. What do you guys think?