The Wand and the Wizard's Life-force Edit
Again in "Kill, Mark... Kill!", as shown in Leonard Powers's case, the wand is the wizard's life-force. When the wand breaks, the wizard's body explodes. However, it does not kill the wizard.
The wizard's flesh can still regenerate back to the original wizard if all the pieces are put back together before the regeneration starts. Otherwise, each chunk of flesh becomes a tiny baby wizard. Each time one of the tiny wizards dies, every other tiny wizard grows a bit larger and older. So for the complete rebirth of the original wizard, all tiny wizards but one must be killed.