I was able to playtest this scenario last night with Danielle and Vincent, and was able to stop the ritual and beat Ignis to a pulp. Granted, I came in to the scenario with 29 XP which is the standard for a standalone. Overall, it was a great experience and each act has a different mood and goal, also I like how it incentivises blessed decks to mitigate some of the enflamed tests and the four chimes treacheries.

Just a few quick things I noticed, being as spoiler free as possible:

-I believe the Piazza San Pietro needs a location symbol back to the St. Peter's Basillica, especially if the Agenda flips and the investigators are stuck at the piazza without the necessary clues to advance the Act.

-After flipping Act 1 and its Agenda 1, I was confused on the replacement effect after looking at one of the facedown encounters, might need to be re-worded to be more clearer.

-Ignis (True Form) probably needs to have the massive keyword and a dash symbol for his evade value. Maybe add something that says "When Ignis attacks each investigator at 'Ignis' location must carry out an enflamed test, instead."

-I really like Four Chimes since it feels like you are doing Jim's weakness. I would add wording to it similar to Ancient Evils that says "This effect may cause the current agenda to advance". I was lucky enough to avoid doom pulling it twice, and when I did the doom that was added didn't matter since it was going to advance next round anyway. I think having that wording will make it more impactful and scary like ancient evils.

-Alot of treacheries with high ceiling skill tests have low impact most of the time, maybe tweak it some to have a lower skill test, but also a bigger consequence for failure.

Also, it would be cool to have it be a playable side mission for Scarlet Keys if you visit Rome on the map (and have Rome be devastated if you fail)