Season 4 promises tons of great changes for Diablo 4 and we can even expect a worthwhile reward for defeating Uber Lilith. After killing Lililth at least once in Season 4, she will drop a Resplendent Spark that can be used to craft an Uber Unique. Crafting these items requires at least five sparks for one item, but that’s still a much better reward than what the Mother of Sanctuary provided before, which is next to nothing.
This information comes from a Reddit post from user greenchair11. In the post, they say that it would be a good idea for Lilith to drop a Resplendent Spark as a reward so she’s finally worth fighting. Many of the comments agreed and the Global Community Development Director, Adam Fletcher, commented as well. “This is the plan. It just won’t be present for PTR,” he said underneath the post. So we won’t see this change in the patch notes or the PTR but we can expect it in Season 4 or soon after.