Ambrus
Explorer
Keep in mind that the "quarter of all black dragons" figure is simply V's wild ballpark guess of the spell's full effects; issued while trying to stick it to his/her defeated foe. The true figure could be significantly smaller, bigger or even truly genocidal if V's knowledge of draconic genealogy or procreation isn't quite accurate.Btw now we know the spell was essentially genocidal since it wiped a full quarter of the Black Dragon population.