This is not another dicussion on wether or not Cerilian (or any wizards)
can function outside thier home worlds. I have a little question
concerning that issue, but all I want to know is: does it sound
good/work in your mind?

Background (skip if you don't have time):
In my RL campaign, my players are mostly FR fans but since I vastly
prefer BR, I DM it and not FR. Well in an attempt to appease them, I'm
throwing in a bit of FR (but BR will have a heavy infulance). The
players will soon be in the foothills of Tournen, where they will meet
an old man in a tall cap and a torn cloak. He is Elminster. Mr. E was
looking for new planes to explore (ya know, no dragons to mulitlate, so
what else are you going to do on a Sunday morning?). Well he teleported
to Cerilia, but ended up in the Shadow World (IMC, all plane-hopping
into and out of Abyneris must be done from or to the Shadow World). He
found that his spells were useless and fled the undead that were after
him. Luckily a halfling had just created a portal and Elminster darted
into in. The halfling and Elminster (with his non-functioning Specially
Modified Staff of the Magi) fought the undead that came through. The
halfling was killed and Elminster was left to wander. The PCs find him
and (to make a long story short), Mr. E joins thier party cause there
are no mages in Cerilia (save the Sword Mage) who have even tried
plane-hopping. Now I was originally going to restrict Elminster to no
spells at all (for obvious reasons), but I am considering allowing him
to access Lesser Magic.

My question: Would it be logical to allow a mage from another plane to
cast only lesser magic? Note that my reason/explanation for not
allowing all spells is that Cerilian wizards "mine the mebhaighl" while
other wizards get it from the land (DS) or the god of magic (FR). Would
it make sense if I said that the Shadow World screens off True Magic
from the "conduit" of magical power the off-world mage draws from his