Grey Crypt Level II - Spoilers
The mage at 4n/11e opens the magic doors at 6n/16e and 4n/18e. 
The mage at 4n/21e opens the magic doors at 4n/14e and 2n/16e. 

Grey Crypt Level II - The Death Snare
Visit all four magic mouths in this order: Southwest, Northwest, Southeast, Northeast. Repeat two more times. When you step onto the Northeast mouth for the third time, you get the segment and then you get teleported to 0n/1e on the entry level. 
