If the target creature or planeswalker is an illegal target by the time Vraska’s Contempt resolves, the entire spell doesn’t resolve. You won’t gain life.

There are many important moments in the story, but the most crucial—called “story spotlights”—are shown on cards. These cards have the Planeswalker symbol in their text box; this symbol has no effect on gameplay. You can read more about these events in the official Magic fiction at http://www.mtgstory.com.