source: Seventh sons have strong "knacks" (specific magical abilities), and seventh sons of seventh sons are both extraordinarily rare and powerful.
target: Seventh sons have magical abilities, and seventh sons of seven sons are even more powerful.
references: Seventh sons have magical abilities, and seventh sons of seven sons are even more powerful. Seventh sons have magic skills and seventh sons or seventh sons are really rare and strong. Myths believe seventh sons have magical abilities and the seventh sons of seventh sons are even more powerful and rare. Seventh sons have magical abilities, and seventh sons of seventh sons are extraordinarily rare and powerful. Seventh sons have strong magical abilities. Seventh sons of seventh sons are rare and powerful. Seventh sons have strong "knacks" (specific magical abilities), and seventh sons of seventh sons are very rare and powerful Seventh sons have strong magical powers.  Seventh sons of seventh sons are very rare and powerful. Seventh sons have specific magical abilities, whereas sons of seventh sons possess rarity and power. Seventh sons have strong "knacks" (specific magical abilities). Seventh sons of seventh sons are both extraordinarily rare and powerful. Seventh sons have strong skills, and their sons are very rare and powerful.