It'd be awesome if monsters could spawn teleporters/caves, similar to the way that Leprechauns did in this past St. Patty's day event. Instead of holiday specific prizes, maybe a chance to get that monsters statue? I think it would take a lot of the monotony out of grinding.
Yeah anything that encourages exploration and more roaming of the world would be awesome. Even spicing up random camp spawns would be nice.
I briefly talked with Telamon on IRC, and the issue with caves and instances is space and the fact that they need to get created by hand...hence the limited number of them. I was hoping it was possible to just sporadically change the spawn type in the leprechaun caves. So, for example, if you'd been farming gargoyles, there's a chance that one would open a gate to a gargoyle populated cave.
