Finally found them.
There are two enterances to TD from Lavaspinner's Lair. Fortunatly, the easiest way is the one nearest the LS ZI.
You zone in at the edge of a cavern. After you go in for a little bit, you will see a huge room. In the middle of the room is where all the basilisks spawn.
Some caster mobs in the zone see invis, including the Evokers.