Glacirius brought suggestion about PvM arena
We can use mobs already on server. IDK if plain as they are on server or slightly tuned..
mobs shouldn't destroy things like mesecon button, torches (or another light blocks), maybe also obsidian glass
mobs should drop some special item (coin, badge, something like that) which will be tradeable for some special items in server shop
we can transform zombie into “Notch” mob which will be dropping cups of coffee (it can be stronger than zombie maybe) (Zel maybe can do skin)
In arena will be button (or more buttons to spawn certain mob/mob combination) (button must be protected to not spawn enormous count of mods when someone will be pressing it frenetically)