An asterisk next to the mention of the "blood of the innocent" caught her attention. At the bottom of the page in tiny print she could hardly see was an important caveat. The potency of the spell, and thus the likelihood of it succeeding, would be improved by using the innocent blood of the spell-caster's own child. If it wasn't possible to use one's own child either because there wasn't one or none of the ones available were "innocent" enough, a sibling or niece or nephew could be substituted. Though not necessary as any innocent child would theoretically work, it was highly encouraged.