If I have the Wand of Terror from the Dragon Expansion and I encounter a space with multiple enemies on it, can I use the wand separately on each enemy? Or is it used once on the combined total?

I'd say no but I think it's a motivated question..

You could even argue that you can only use it when you are about to engage just one Enemy (" an Enemy" = singular) but... nah

Anyone else got a good solution for this?

You may use the Wand when you are about to engage an Enemy in battle or psychic combat. Roll 2 dice. If the score is equal to or higher than the Enemy's Strength or Craft, move the Enemy to any other space in this Region. If it is lower, resolve the attack normally.

http://www.talismanwiki.com/Wand_of_Terror

Yeh I tend to agree with this because it says "an Enemy" you may only use it against one with multiple enemies.