When I first did Nightfall, it was Summoning Pits with solar burn. I was a 29 and the NF was 30. We got to Phogoth and we were in the first room. We had him at less than a fifth of his health, and I backed up into the room behind it, thus, resetting the entire fight. We ended up dying and having to restart the entire thing. Keep in mind this was about 4-5 weeks after release so we all sucked lol