Okay, I'll take that bet. What do you wager? Let's try it and see.
The most fun I've ever had in UO was at the Trinsic invasion where developers took a live hand in the events. I can't count the number of times I died to the "Boss" and still had fun! The Brit invasion was a close second, and that was within player housing areas - where the home owners often gave refuge and resurrection to players from the invasion. And if the mobs in Luna were really such a big deal, keep them out of town - that's no excuse not to have another fun event that most players enjoy.
I won't argue there, the Trinsic undead invasion was epic. I think part of the reason it was so great was that stealing silver vanq weapons was like taking gruel from a mongbat. We are going to try and capture some of the essence of popular past events *coughs* Treasures of Tokuno *coughs* with upcoming content. One thing to keep in mind in adding new dynamic content (like an invasion) is how it might effect someone's home. I don't think anyone is too keen on showing up to their house on a crafting mule, their beetle's back breaking under the load of boards they just spent 2 hours harvesting, only to get one shotted by some mob that wasn't even spawning in the area the previous day.
