How about being able to buy a henchan (one or more) that will last for an entire dungeon? My kids wanted to spend crowns on each level for henchmen, I ended up helping them. Allowing a henchman the ability to travel the entire dungeon would be awesome. It may cost a bit more (depending on the dungeon, I would imagine), but it can make the difference of getting to the last level and losing and getting upset, or completing it. This may help the people who like to solo be able to complete some of the 'impossible' towers/dungeons. Malistaires tower would still be impossible to do solo though, due to the crystals and such. Just tossing this out there.
