We've had the intent to do this for events for quite awhile!
I fancy myself pretty good at dramatic landscapes with world-painter, ive been making a handful of things for lotc ~
However, any player could build a fantastic location and use it for an event purposal - we'll throw it on a seperate world and link the with boats -
The adyton dig site is similar to this idea, we slapped it together in 2 days and theres some great atmosphere and tons of to find !
*Edit* We can make an official event section on the forums for this sort of thing aswell, ill post up some of the terrain ive made aswell as take ideas / concepts and create them for players to build upon!