User blog comment:IamJakuhoRaikoben/Chapter 471: Until the Battle is Done, Review./@comment-25324252-20160201211858/@comment-7418318-20160202095207

Speaking of metal I just thought of a way that Laxus might affect Wahl, though it's more for hindering his movement rather than a finishing blow.

Magnetism.

If he can use his lightning magic on a big enough pile of metal he might be able to create an electro-magnet to slow or even immobilize Wahl, assuming Wahl's inner workings are made from a metal affected by magnetism.