I have only found 3 magical rooms so far. I have only been playing for around 10 hours.
1. magical room#1 near the fairy Tinette in the crystal cave 2. magical room#35 in Waterfall Cave 3. magical room#36 in Elijah Woods near where you see Bokden. It is near the top in a little alcove area.
I found one in frozen woods... Behind the first(I guess) unicorn statue there is a crack if you press enter in front of it you will get transported to MR#3 Inside there are (R,S,L)