other than, “don’t,” what advice could you give me on DMing for a group of 9-10 PCs. Assuming you mean 9-10 individual players?

Keep in mind combat rounds will be very lengthy even if everyone moves pretty efficiently. Consider using a round table initiative order instead of rolling. Save yourself that work.

— Dan Dillon 👥 (@Dan_Dillon_1) February 21, 2020

Yes, 9-10 active PCs at the table at any given moment. I am running Descent into Avernus, and it’s my first hardcover. How much play do I have in terms of encounter difficulty since there are just so many PCs? What are some ways to make it challenging and still engaging?They will frogstomp almost every encounter unless you split the party into different encounters (run are the same time), or way increase the difficulty.

Increasing the difficulty will make encounters take an incredibly long time, most likely.

— Dan Dillon 👥 (@Dan_Dillon_1) February 21, 2020