From 5 up to 15. Strahd was increased due to the party having an insanely powerful npc, who, while curtailed, help lead the party here. They are enjoying the changes made, like adding the mists and two oblexs (one of which was an elder that they almost killed) though two members have died. Death was expected since the adventure started with the phrase: death will happen when mistakes are made. If the party wipes the adventure ends, with 2 d10 rolls to dictate when they can play strahd again. Its been a tradition in our group since it first came out in 5e. In a way you can probably call it our very own dark souls dnd.
For those curious, the first member died when he failed a con save for the 5th time against the mists. In one combat. The second from a disintergrate when the alhoon peddler revealed the replacement character amongst his wares when I was trying to get them some easy magic items. The barbarian attacked the alhoon after purchasing some superior healing potions since he thought it was a slaver. It wasn't. The barbarian didn't care. Fight ensued, party backed the barbarian and eventually the alhoon dusted the party member. The replacement character reasoned with the alhoon that it was a misunderstanding, landed the persuasion, and it took its crap and left.
