Answer: The champion who says “The first time I returned from the void, it was to save me. Now it’s to save them” is Kai’Sa, Daughter of the Void. Of course it is. You might have been thinking Kog’Maw ...
The other way to access them is by opening the map and clicking on the purple Void Intercept buttons on the bottom left of the screen. Also read: The First Descendant tier list: Who are the best ...