There is no Vanessa altar in the Dungeon yet, but besides from perhaps obtaining her soul splinters as giveaways, we can obtain one splinter by scoring 400K in the emergency preparation event. Perhaps it is the only event that offers a soul splinter as the highest tier prize because soul splinters are usually a leader board prize. My strategy is always having lots of demon souls to recruit sky city troops with the preparation buff and use the speed ups. Since I do not buy things in this game, I just accomplish it for a few times only. So good luck to you all.
