Change the structure of the 4-dungeons, maybe?

[Molic]

Snip

I think one way to combat that is to have entirely different game modes. Kind of like First person shooter (terrtories, capture the flag, search and destroy, etc). For they dungeons we have now we could call that mode: classic dungeon

Then we could add like tower defense style mode, a horde mode, you could have where the players turn into monster and have to stop adventures or bandits type of mode. Boss battle mode, etc

If you went about it that way, they could probably even rework a lot of the older dungeons and give players more variety.

Players could then just que up for there favorite mode, like they do in FPS games. Or have a mode roulette.