Bloodline magic and ritual magic were both ancient forms of magic.
With the advent of alchemy, ritual magic, which was closely connected to it, had survived and developed to the present day.
Traditional bloodline magic involved merging with fantastic beasts, a process fraught with uncertainties and risks that could even produce problems such as "hereditary family curses."
As a result, much like the predicament Animagus magic had once faced, it had become a relatively niche form of magic.
When most wizards needed to conduct related research, they generally settled for studying branches derived from bloodline magic, such as certain forms of healing magic.
After another round of discussion, Wizet realized that these broad overviews really were no more than the basics of bloodline magic to him.
After all, through a memory left by Salazar Slytherin, he had followed in Salazar Slytherin's footsteps, learning step by step what bloodline magic was in the most direct way possible.
Later, he had brought the basilisk into the Mirror World and received personal instruction from Salazar Slytherin, deepening his understanding of bloodline magic and allowing him to study it more effectively.
For the Champions, however, studying such a niche form of magic-or even observing a bloodline magic experiment-was no easy task.
The Champions each had different reasons for encountering bloodline magic.
Fleur Delacour, for instance, had expressed herself discreetly, but Wizet had understood what she meant: she had learned bloodline magic to make the most of her Veela heritage.
Victor Krum knew magic related to blood, and in pursuing a deeper understanding of how blood could be used in magic, he had inevitably encountered bloodline magic.
Pukwudgie Academy trained healers, and its relevant magic courses covered subjects connected to bloodline magic. That was why Charles Graves and his fellow students knew about it.