they're called interdiction torches, they cost a diamond or two each to craft but they actually physically propel mobs inside of their light radius away, that's why the base is open air with no doors yet completely safe at the same time.
the round things on the walls are teleporters from thaumcraft, the ones on the floor heal you.
that world isn't quite legit though if i'm honest, i cheated myself a destruction catalyst right off the bat with NEI.
here's the torch recipe so you can see how much they cost, the thing in the center (an EE item called the philosopher's stone) isn't consumed.
