BeardFan said:
I think you can easily do a houserule for that. Enemy player draws 8 cards. Plays 1 card for each player on the stage zone (plus additional cards required by some effects). Enemy player plays shadow cards for combat. Enemy player fills up hand to 8.
The variable is the number of cards the Enemy player can hold. More will make it harder for the heroes, less will make it easier.
Or something like this
Don't know if it will be fun for the Enemy player, though.
I think you could probably work something like that but, but if the encounter deck had objective cards - like the key or a clue for gollum, they'd need to be some ruling that prevented the DM keeping those cards in his hand indefinitiely!