This is less a bug and more just something the programmers seem to have missed. The autotap seems to place too high a priority on leaving blast zone up. It is often my last land up when I have colored spells to cast, and ive lost a game more than once by being unable to cast a cut down, etc despite having an untapped blast zone and having my black sources autotapped previously to pay generic costs. There really is no reason to activate blast zone for x=0 that I could imagine short of being forced to by a mindslaver, etc in order to squander resources, in which case tapping for mana is equally effective. If you dont have at least 2 other untapped lands, an untapped blast zone is no better than a basic wastes, and the autotap formula needs to be adjusted accordingly. No wonder this card is so seldom- and poorly-used when it can't even be made to work properly.