What do I mean by that? Well first of all it'd be a thing that's available only in endgame, so yeah I don't want to see no 'It'd be too broken, imagine the farming potential' arguments. It's endgame and you don't need to farm anything extra.
What I'm talking about is the ability to place down things like hound mounds, hollow stumps, spiky trees, boulders, merm huts, slurtle mounds, monkey pods etc.
That way people that like building megabases could create some interesting new biomes. Like rock biome filled with slurtles or a species of monkeys living among spiky trees.
You'd be able to do that thanks to a new crafting station which you'd aquire after defeating the final boss that RoT will have to offer