Biggest Tip: Build and play how you want. Want to give your tombs away for free? Do it. Want to block them off entirely? Do it. Personally, I think just blocking them off is a waste when you can use them in some way for a trap, get the player to search for them in hidden places, or even be generous with them, but don’t let me or anyone else tell you how you should build.
Having said that, you probably want to find a decent balance somewhere in the middle of “Must get all the kills in any ways possible for loot” and “Want people to finish my map so I get accolades and loot so be merciful a bit.” You don’t lose anything from other’s success (Unless you’ve put your base in Overdrive mode anyway) so you want them to beat your base sooner or later for those sweet accolades/resources from accolades.
If you want to make some really good bases and delve real deep into base designing, it might be worth looking at some video game design philosophies and how devs go around building lairs and dungeons in other games. A lot of people tend to have fond memories of say some of the better Zelda dungeons. Look at em and ask yourself “What makes this work? Why do people carry on with it vs rage quitting? How can I apply lessons here to my lairs?”
Sometimes, you should totally ignore tips 2 and 3 and just fugging experiment. You can have up to 200 lairs, spend a few of them just making your crazy death trap or labaryinth lair or other weird idea you had. If it don’t work, change it. If it does, great.
Only activate Overdrive Mode if the Genmat you are getting from kills outweighs the Genmat you lose from their success.