but wouldn't kalstar (from ebberon) be
a) immune to it's nasty thing-a-ma-gigger,
b) by your reasoning, not be able to manfest/cast?

thing is, kalstar(excuse my spelling) don't dream, and why is dreaming related to casting anyways?

if you printed off all the monsters you have made, organized them by CR, then when your characters reapeadly beat your favorate,(of the aproprate level) then you just pull the next one off the correct stack and say "that storage for rent space was worth it!"