Taking a direct hit from a double-layer Fireball Technique—even with the Elves' physical constitution far superior to humans'—severe injuries are inevitable. Even though the Elf Clan excels greatly in potion-making, getting out of bed would still take at least a month.
The extremely short distance means the one being attacked has no chance of reciting complex magic—even for simple defensive magic, time is extraordinarily urgent. Under immense mental pressure, mistakes become highly likely. And once a mistake is made, there's no escaping the strike anymore—no opportunity to retaliate at all.
For ordinary Elf Mages, this is nothing short of a nightmare. However, it remains only a nightmare for ordinary Elf Mages.
