Dark Souls II Boss Guide: The Rotten
The Rotten is absolutely disgusting, so there is that. The most difficult part of this fight is the environment. Unlike the Iron King, the fire won’t kill you instantly but it chunks you very quickly if stay in it - so don’t do that. For a mobile type character, stick close to him and dodge his slow attacks as they happen. He has a three swing combo so watch out for that. His two most nasty moves is a power up melee which lands later than you think and a quick nova. When he charges up for that nova drop lock instantly and book it. Like most bosses, I find it easier to roll behind him to maximize punishment. If he does a gross puke move, END HIM.