Went to the sewers, invoked 2 phantoms, and we killed the rat, then a black phantom attacked and we killed him, we went even lower and killed the dragon.
Then I ventured into Blighttown, holy **** that was scary, so dark, dangerous and with a horrible fps, I managed to reach the first bonfire somehow, and I invoked a phantom to help me advance. We went down slowly but steady, but at one point climbing down a ladder, I got infected with some toxic crap that was eating away all my life, that made me spend all my potions, and when I took the last one, I discovered a cure in the inventory, I ate it just in time, but I was one hit away from dying and we still had to cross the poisoned swamp and kill the Spider Witch, so I let my phantom go always in front of me.
We managed to get down and cross the swamp, there was a new bonfire there, but the game didn't let me lit it cause I was in coop so I couldn't refill my flask, so I was still ****ed, no bonfire for me, however, I activated a new summoning sign there and I got a second companion.
We ventured towards the boss and we got invaded by a black phantom, which we killed (My companions did, I was just ****ting my pants in a corner cause 1 hit would mean death to me) Killing him gave us a massive amount of souls and 3 humanities. I used one to re-fill my health and we continued towards the boss. That black phantom was a saving grace for me.
The spider witch was sexy but scary, since I entered first without any previous knowledge, I just tried to dodge, but the fire got me and almost killed me, luckily my companions arrived in time, and we managed to kill her by surrounding her and attacking from all directions.
I guess that playing alone all those areas would have involved lots of retries.