[Pursuivant]

What traits a GM allows players to buy after play begins is entirely campaign dependent.

In campaigns where the characters are experienced adult professionals and Magery is inherent and immutable it should be virtually impossible to acquire levels of Magery after play begins.

In campaigns where characters are children or beginners and/or the genre conventions demand that PCs' powers blossom during play it should be possible to buy levels of Magery as "Power Ups."

For example, in Dungeon Fantasy, buying an additional level of Magery is a quick way to represent "leveling up."

In cases where the GM wants to split the difference or demands "niche protection" for the PCs, mage or would-be mage characters should buy (additional) levels of Magery as Potential Advantages before play begins.