The only things that ever stand in the way of Black Adam and his power are a lightning bolt and a word. By vocalizing the name of the wizard Shazam, he can shift back and forth between his superpowered and powerless states as often as he pleases. If he moves out of the way in time, he can even use the lightning bolt that morphs his body to attack anyone within range. However, the word must be outwardly expressed for all this to work — thinking "Shazam," for example, won't pull it off. Furthermore, it's likely normal lightning can also trigger Black Adam's transformation, as it does with his foe Captain Marvel Jr. in "The Power of Shazam!" #14 by Jerry Ordwary and Gil Kane.
When Black Adam was reintroduced during DC Comics' "New 52" era, it was established that he could demonstrate a greater control over his magic lightning, capable of generating it from places like his eyes, hands, and the lightning bolt insignia on his costume. However, this lightning doesn't necessarily trigger transformations in others powered by the wizard. In some cases, it can actually be used for transmutation, as when it makes the villainous Ibac a stone statue in "Justice League of America feat. Black Adam" #7.4 by Geoff Johns, Sterling Gates, and Edgar Salazar.
