User blog comment:IamJakuhoRaikoben/Chapter 361: The Two Bombs, Review./@comment-24066070-20131122224003/@comment-7418318-20131122224528

He can just capture Lucy in one of those spheres and tell Natsu to not defend against his attacks, or he'll kill Lucy along with Michello.

If Natsu doesn't eat the explosions, he's damaged by them and eventually knocked out. Michello is killed soon after.

The only question that remains is, whether Jackal keeps his word and leaves Lucy unharmed, or blows her up, leaving her badly hurt.

That's be a nice way to salvage the situation, even though I doubt it'll happen.