[hider=Phardax and the Imp planning the dungeon][img]https://i.imgur.com/XGpdV9f.gif[/img][/hider] 
I think a Tier 1 lock would work well. Keep people out of areas we don't want them to go in. 

A tier 3 mine with missing components might be neat. Gives us some materials whilst helping us expand. What say my fellow ne'er-do-wells?