Here is the latest journal. The group said when they went in that they would explore level by level, but now that they are backstage they seem to have gone down 3 levels without any worries. I wasn't on my best form on that evening, so I made a couple of mistakes - the big one being that I misread the effects of the throne so didn't give Javlin a saving throw. When I realised my mistake I gave him a saving throw, which he succeeded in, so I ruled that he kept the temporary hp but lost the beserk rage.
They are now about 3 levels further down than I thought they would be at this point, so I need to do some good reading to make sure I am familiar with what they might encounter in the next session - especially level 5 which seems really complicated.
https://app.roll20.net/forum/post/7499846/days-115-116-deeper-into-danger