Depictions of the speed and extent of injury to which Wolverine can heal vary. Originally, this was portrayed as accelerated healing of minor wounds, but writers have increased this ability over years to the point that he can fully regenerate nearly any damaged or destroyed bodily tissue. One of the more extreme examples of Wolverine's healing factor shows the total regeneration of his soft body tissue, within a matter of minutes, after having it incinerated from his skeleton.[19] Wolverine survives the explosion due to the protection his adamantium-laced skull provides to his brain.[20] It has been stated in the Xavier Protocols, a series of profiles created by Xavier that lists the strengths and weaknesses of the X-Men, that Wolverine's healing factor is increased to "incredible levels" and that the only way to stop him is to decapitate him and remove his head from the vicinity of his body.