Chasing Lazarus

This event will trigger during the boss fight against Lazarus at the Sanctum of the Bat God. When Lazarus drops below a certain fraction of his health, his concentration on the binding ritual will fail and he will use the confusion to escape. He does so by turning into a dire wolf. He will decent a set of stairs on the east side of the building, ending up all the way down in the third courtyard. He will then find a cave that leads outside of the sanctum. If the party loses sight of Lazarus at this point, they can track him using a Wisdom(Survival) check with DC of 8. Tracking Lazarus through the cave does not require a DC, as the trail of blood he leaves behind is very clear to follow.
The cave will eventually end in the thorns wood. It is here where the trail becomes slightly unclear and a tracking roll needs to be made to follow the vampire. The check succeeds on a 10 or higher. If the players fail with any roll except a nat 1, they will get lost and stumble upon the teleportation altar that lies in The Thorns Wood. Otherwise, they will find their way to a large cave entrance. The entrance is surrounded on both sides by two giant stone statues of hoplites carrying a shield and a spear. The spears are positioned to cross each other above the cave entrance. This is the entrance to the Caverns into the Depths. The blood trail leads further inside, past a giant stone door that has been opened slightly. On the door, a bloody handprint can be seen, likely from Lazarus. Not much further, the players will catch up to the vampire, laying on the ground bleeding out. He is still conscious but does not have the strength left to fight off the party. Upon being asked for his motives, Lazarus will answer that he wanted to gain a high standing within the new demon hierarchy that will be created once Arenez returns. He wanted to do so by claiming the power of a vampire ancestor. At any point the party can kill Lazarus, completing the quest. 
If the party wishes to venture further into the cavern, they will reach a dead end once the cave leads to a large open room. The room has a broken-down staircase that used to connect to the entrance through which the players arrived. Without the staircase, the drop is too high to descend. Additionally, a giant demonic spider is asleep in the room, further keeping the party from progressing.