Lightning staff was removed from RuneScape after an update, but still exists in-game for those who had obtained it.
The lightning staff is an item that could be obtained by purchasing and redeeming a $25/£20 RuneScapeGame card from 16 November to 2 December 2012 or by buying the gold premier club between 20 December2012 and 31 January 2013. Upon redeeming the card, you would also unlock the "Professor" hairstyle, and the lightning staff emote. This staff has four level variants - level 1, 20, 40, and 60 Magic required - which can be switched using the "Change" right-click option. All versions provide unlimited air runes.