I know it's safest in a Large Keep and Fortress... EQ cant reach the pit or casters. However, I am trying to promote a town and its associated citizens, hence I feel I should hold the session IN that town. What Say You? This event would be open to the public, all can attend. ALL factions included.
It is do-able. You could mitigate disruptions in a variety of ways. Primarily, you could reduce the target area to a 2x2 instead of a 3x3. Setup a healer on the casters, just in case. With a tower the 2x2 is cake, because the doors are double wide. Just leave them locked, ghost entry as usual, casters offset upstairs. Hit me up if you want some security consultation.
I would heed Blaise advice, he has been hosting resist parties since the server was an infant. Good luck with it, be sure to let us know time and date, etc. Love player towns, think they add so much to server. Westra/Marjo Governess of Wispfelt