Hero: Powered by Love? You? You of all people, your most powerful magic, the attack that can devastate an army of battlemages, reduce a warded fortification and everyone in it to dust, and you claim it's powered by LOVE?!
Villain: Yes. Divorce rates go up measurably every time I use it.
(Bonus if it's a twisted form of a spell that would usually be fueled by the user's love, without consuming it) -- RecklessPrudence
"There's no love spell in the world that causes that much chaos and destruction," objected Hero. "Love is a building force. Not destructive."
"Well... I must admit I tweaked it a little. And it works! I use all the love my thralls have to win ultimate victory and you... you... you... Hero... have been draining my batteries!"
"You perverted the course of love magic for your own ends..." Hero was having trouble with this concept.
"Yes, little miss hack-and-slash. Not that you could possibly understand. Intelligence is usually a brawler's dump statistic, isn't it? You doubtless think the entire world is meant to run on only one set of rules." Vil'ain smirked. "Rules are for the weak."
"Unfortunately for you, intelligence was never my dump statistic. And you forget that you've also been draining any and all love that your thralls have... for you." Hero nodded, drawing her sword. And Vil'ain's formerly loyal guardsmen did likewise. All blades pointed towards Vil'ain.
"Er," said Vil'ain. "Let me check my notes?"