This mod adds the Illusion Block (and its ethereal version) from this good old Ars Magica 2
For those that didn't play with that mod, the Illusion Block mimics the texture of the block in front of it but also allow player to walk through it.
So basically, you can hide rooms behind some of this walls.
There is also a solid version (the ethereal version) of it where you can't walk through it.
I also added a new mechanic about these blocks, illusion blocks can mimic other illusion blocks already mimic-ing blocks. Chained illusion blocks have a maximum length of 32.
