Selphira finally reached the range where she felt most comfortable using her devastating attacks.
It wasn't that she couldn't launch them earlier or at greater distance than the novices she was about to face, (after four hundred years of experience, her range surpassed that of any other tamer present), but rather a matter of pure efficiency.
Launching mana at long distances was considerably more costly than using it in the immediate vicinity, and besides, she had a powerful beast that required proximity for maximum effectiveness: her Gold 2 White Serpent.
It wasn't the most powerful beast or the most defensive she had, those titles belonged to the other creature in her arsenal, but it was the one that moved fastest and created the most "waves" of destruction when deployed appropriately.
That's why Selphira preferred using it to overwhelm this kind of soldier formations when they were densely grouped.