SPOILERS
You have to get through that tower in order to access a necessary boss, although there may be a shortcut I haven't discovered yet...but anyway to be completely honest I just booked it through that entire tower to get to the boss. I actually found that area to be maybe the most frustrating area of the entire game (the lead up to the King dragon boss). The only area in DS2 that reminded me of Sen's Fortress in DS1. Good luck Melf...that area cost me the most deaths by far.
I recommend running through that Belfry, until you get back into iron keep (through the mist at the end of the Belfry), then keep running until you reach the turtles in the tunnel where you're basically forced to fight them (the second tunnel, not the first tunnel), turn around and destroy the knight who will be rushing at you from behind your back, then take out the turtles, be careful with the fire spouting machines and then one more turtle and then you are golden until you reach the boss..who will most likely kick your ass again and again. Summoning HIGHLY recommended. Fuck that area...I love it though...as I said good luck

