The Corruptor with this skill gains an innate melee attack, Tainted Wings (this keeps Razor Wings available as a separate attack). This attack deals 13 points of Unholy damage.
In addition, the Corruptor may imbue their Tainted Wings with an Offensive Spell by using a Spellgem containing that spell. Doing so costs 3 AP and destroys the spellgem. Further, imbuing a spell overwrites any other spell which may have been previously imbued.
While a spell is imbued in the Corruptor's wings, each attack with the wings will cost the Corruptor an amount of MP equal to the spell's base casting cost. If the Corruptor does not have enough MP, then they will not be charged and the attack will deal the usual 13 points of Unholy damage. If the Corruptor does have enough MP, then the attack will deal Supplemental Damage equal to the spell's base damage.
A Corruptor can remove the imbued spell (without replacing it with a new one) by attempting to imbue their wings with a non-Offensive spell. The spellgem is consumed as normal, and further attacks will neither deal the supplemental damage nor charge the Corruptor for it. This will remain the case until the Corruptor imbues their wings with an offensive spell.