Hm. This is odd. The BovD has a separate list for the corrupt spells to illustrate that they can be taken by all spellcasters. Meanwhile, the LM lists the cyst spells only as cleric and wizard/sorcerer spells (assasins, for instance, do not have it on their list). The feat is a necaessary prereq for clerics and wizard/sorcerers to cast them, that is all.
Well, whatever, can certainly be ruled adept-friendly.
However, I kindly ask you all to cool down here. Mistakes and misinterpretations have been made on both sides of the argument in this thread.
Thank you
- Giacomo