As it turns out, the throbbing cock did not indicate the Demon Lord is going to cum inside of you. Though, it usually the signal for it.
However, for Rumella, the throbbing cock did something else.
The blonde feel it first as jolt of electricity seem to shock her pussy. At first, she thought it was just the result of the Demon Lord making sure there are no space in her pussy.
However, as Rumella noticed some subtle difference, she used the little knowledge she had on Magic to detect any form of mana circulation.
And she was proved right as some sort of spell seemingly starting.
"W-" another cut sentence, Rumella changed whatever she was gong to say to wild screaming.
It was of no surprise, with his cock pulsing in Lightning Magic. And not just any Lightning Magic, but one infused with Lust Magic.