Imagine placing structures in various areas that require frequent repair or maintenance using local resources.

What if those structures had tactical significance?

The most tame would be a bridge or a dam. More dramatic would Siege Weapons granting buffs or occasional damage to support combat classes. Or perhaps a barrier preventing an enemy spawn point from activating?

There's often a certain balance to a region, having a bunch of monsters spread out to fight one or two at a time. Very chill, almost TOO chill.

What if there wasn't though? What if the enemies were endless? What if the actual strategy wasn't even to defeat the enemies? Instead consider sanctioning the strategy to leeroy jenkins it, to use some sort of Crowd Control and run and cut the bridge behind you or something. Maybe against a timer even.

That would increase the pressure and the drama while inviting opportunities for non-combat classes to have a bodyguard escort.

If fighting through an area required a coordinated effort to maintain a foothold, then there would be a natural need for momentum.

This would make it so non-combat classes could experience some tension.