Which move of Undertaker was once banned and then made legal?

Hell's Gate, The Undertaker's submission finisher (a modified gogoplata), was briefly banned by WWE in 2007 after a segment where it appeared to cause legitimate injury to an opponent. The move was reinstated later with modified execution. This makes it the correct answer. Tombstone, Last Ride, and Choke Slam are also his signature moves but were never banned.