Since elves can cast true magic (but not realm magic unless they're
blooded) any elven wizard who crossed over from another setting should
be able to keep casting his spells.
Human and half-elf crossovers would first have to become blooded before
they can cast true magic (killing or investing). A general mage should
be able to use his 8 &9 th level illusion spells to trick somebody into
investing him or make an easy kill. The only problem is that he first
has to figure out what is happening. When the first spell he wants to
throw in Cerillia is fireball to keep those goblins away he is going to
be quite surprised.

Jan Arnoldus