That would probably have worked without too much effort to begin with too. Between the Vaels, perhaps because she was the youngest, or she'd been relatively sheltered due to having been named as the crown princess and trained for it from an early age, Ellie tended, for all that she was smart and people said it, to be rather too trusting for her own good. And since it had rarely bitten her on the ass before, she saw no reason to think that it would do that here.
Besides, Lucifer had gone out of his way to be kind to her without being creepy. You had to trust people like that. She'd be willing, probably, to do him a proper favor along the way. Though they may want to wait until she had a few more skills built up. There was POTENTIAL and magical energy now, but skill? Not quite so much right now.
"And I move my hands...here?" Ellie asked, tossing her hair over her shoulder and getting it out of the way before trying out the words, louder, for the incantation. Hopefully, summoning would be a success.