While playing as the Infernals, I noticed that all the hell terrain in my territory, as well as any other terrain (such as coast) had no food value, even if they normally would. However when I moused over hell terrain in other civ's territories, it seemed that it was still producing the same number of hammers, commerce, and food as it had been before it was converted into it (such as when you mouse over Illian ice terrain, it shows it is producing 2 food). As far as I can tell, the only real damage caused by it is that it removes trees from the tile it spreads to, which could actually good if it spreads to jungle lands. So what exactly are the negative effects of hell terrain? Im sure I must be missing something.....