Browsing through the decks of La Aventura Fantastica I thought it was strange that the Adventure cards featured both terrain and some of the characters. I thought about having the character cards act as new rules although unfortunately their are differing amounts of these cards in each deck so some decks would be more advantageous to play than others. (The Bow deck has four, the Club deck has three while the Hat and Javelin decks have two characters cards.) Mixing cards from other decks to get an even distribution of Hanks, Sheilas and Erics was impossible as there were eleven character cards to divide among the four decks.
One solution is to just play with some decks being more advantageous than others with players rolling a dice before play to determine who picks a particular deck first.
Below are images of the modded cards with rule explanations for them. Each card has a new letter instead of the former A for Adventure. These could be printed as stickers and one of each could be stuck over the cards; reducing the number of Adventure cards from ten to seven. The Bow deck has four character cards so a regular terrain Adventure card sticker would have to be stuck over one of them too.
W is for Ward: (Eric uses his shield to fend off other players.) When this card is drawn the player keeps it to ward off other players from drawing cards from his deck. If another player attempts to pick from his deck whether by using the Bifurcation card or the initial draw from a Dragon card's evade option he will instead miss a turn. If this happens the player must discard his Ward card.
I is for Invisibility: (Sheila can use her cloak to turn invisible and escape dungeons.) When this card is drawn the player keeps it and the next time he draws a Dungeon card he can discard it and not miss a turn. This Invisibility card must also be discarded when this happens.
V is for Venture: (Hank being the ranger and pathfinder can take shortcuts.) When this card is drawn the player keeps it and the next time he draws and discards an Adventure card he can draw another card in the same turn but must now discard this Venture card. An alternative rule could be that the player continues to discard consecutive Adventure cards until a non-Adventure card is drawn.