For instance:

Spawning an npc based on a trigger such as a quest objective or a dialogue (so that you can't kill the npc before you get the quest)

Spawning a placeable object based on a trigger (complete a dialogue asking an npc to build a house, and then the house is spawned)

Despawn and/or spawn placeable objects based on interaction (place a small plant on the map, tie an interact effect to it, interact with it to "water" it, despawn it and spawn a tree)

After a dialogue option, despawn the npc and spawn it elsewhere, or move it

Destroying a quest item after quest completion

Changing the target of a dungeon entrance based on completion of objectives

Also, Take triggers for quests or objectives being the completion of other quests or objectives

With the above I could do things like create a deed item which spawns a quest chain to build up a town by convincing npcs throughout the world to move there and build, have a cave entrance that leads to a cave filled with enemies that could be changed to lead to a cave with miners after a quest completes, replace ruins with new buildings, etc.

The things I could do with that...