The model gains a +4 Ward save. If the model is fleeing at the start of a Chaos Magic phase, for any reason, the wrath of the Chaos gods is immediately visited upon them and they are turned into a Spawn, with the same number of wounds remaining as the character had. If you do not have a Spawn model to replace the character then he simply counts as slain. For Victory points purposes, the character is not counted as slain or below half Wounds unless the Spawn he has turned into is slain or is below half Wounds.