Blood has been a staple of professional wrestling for a very long time, as it has been an excellent tool in amplifying the drama of a match. However, since 2008, blading has been outlawed in WWE, and only on extremely rare circumstances have exceptions been made. In 2002, however, blading was a regular occurrence in WWE, and the Undertaker showed just how crazy those can get, when he bladed in his Hell in a Cell Match against Brock Lesnar at No Mercy 2002. During that match, Takers bladed and soon, his face, and much of the canvas, turned crimson in colour. WWE doesnt want people to remember this because the Undertaker rarely bled, and while the addition of blood tends to make a match more dramatic and exciting, it also makes the Undertaker appear more vulnerable. It ruins his mystique when he appears to have the same vulnerabilities as everyone else. Also, from the looks of it, Taker mightve cut himself too deeply, and bled more than he should have. Fans (and WWE) want the Undertaker to be remembered as this supernatural force that appeared to never get hurt, not someone face down in a pool of his own blood.