Great work, simple and fun, like the board games of my old days <img src="smileys/smiley36.gif" border="0" align="middle" /> .
I think you need put in the game some instructions to "how to play" and the rules, objetives of game, the effects of the potions, etc. Like a Instructions option in the main menu.
When you can take a new hero to the board, only highlight the boxes of the faces, and maybe could be good idea put some statement or notice to inform the player that can take a new hero with that roll.