There is literally no ambiguity in the rules manual regarding when a spell is cast. RM p. 53, "Casting Spells" Part 2, section "F" reads:
"If the caster's final Duel total (the casting total) is equal to or greater than the CC, includes at least one of each suit in the TN, and the caster has met any additional requirements for the Spell, the caster has won the Duel and has successfully cast the Spell." (italics added)
Additionally, this clearly resolves the question concerning if additional requirements, such as Levi suffering wounds, are used when a model resists the successfully cast spell because part 2, section "D" States that additional requirements "must be met in order for the Spell to be cast." Since the spell is cast prior to resist attempts, as shown above, additional requirements are also consumed prior to resist attempts.