Explorers key is horribly buggy in multiplayer.
basically every time I used it, it still deducted the cost of the chests opened from my money, but if it was more than my current money, my money went into the negatives.
and when its in the negatives, you cant do stuff like open containers, use the button to activate the final battle etc.
so pretty much I had to make back like 50K gold on the final level just to activate the final boss fight.
