Ran this adventure for Halloween a few weeks ago, ended up taking my party 2 sessions to get through. Overall, I enjoyed running it as a new DM and I think my party enjoyed it too.

With that said, I think the advice that this is an adventure for 4-6 5th level characters is inaccurate. The encounters designed in the PDF seem to expect fewer characters to be presant, as a 5th level character is pretty powerful.

I will admit, I had a large party of 6 PCs and I let the PCs be pretty powerful, rolling for ability scores and giving them a level 1 feat as well. However, they killed The Phantom in the final fight in a round and a half after I had maxed his HP and given him higher AC.

If you plan to run this adventure I would suggest having the PCs be level 4 and probably limit the number a little more than 6 of them.

This adventure, and the advice that accompanies it, are perfect for a Halloween one-shot! I found that the tips for building up suspense and allowing it to dispate with humor before bringing it back up again were really great advice. The story itself has an interesting backstory which is easily revealed to the would-be heroes, spicening up this horror-themed one-shot. I really love the use of a Doppleganger to lull the party into a false sense of security and trust, only for it to be shattered when that extra person is needed the most. As for my own group (as as per the suggestion of the author), I plan on getting one of my players to play the traitorous backstabbing Doppleganger to help me thoroughly scare the party at the climactic final showdown with the disguised Oni. There are numerous components to this adventure that are really well planned out. So get it and find out for yourself!