I definitely would like maybe little passages or islands in those big acid areas...
How about a halfway lever, that when you pull it some lava or acid puddles pop up, but the whole thing doesn't get flooded? I seem to remember there being one room with acid that didn't just fill the whole place, so while there wasn't a clear passage, at least there were stepping stones of a sort that you could use.
The Angel of Exploration is nice, but if you're worried about getting too much experience on a per-tile basis, why not have a set experience award that's given based on the percentage of the board that's uncovered?
I also like the idea of the coward one, just because it would be a different challenge to have to run past enemies instead of killing them. As far as the XP stuff, I guess you need some way to advance... how about combining it with the Angel of Exploration? That way, you could just run to the exit all the time, but if you risk looking at more real estate, you'll get more experience in return.
Sort of like Angel of Infiltration or something.
Angel of Hoarding
- Start with the backpack