Just traveling to Lago Celeste took us to the 20 minute mark so we knew that we would not be able to complete the quest within the half hour time limit. None the less, we did not quit and trudged on to defeat the right amount of creatures.
The reward for our efforts were:
- Level 90 Experience Cards x 3
- Witch Candy x 3 (it's supposed to give some sort of buff but doesn't indicate what)
- Bloody Coffin (2 day) - It gives Attack +10%, Attack Speed +10%, Movement Speed +10%
- Reverent (2 day) - Gives the same as above.
- Deadly Cross (2 day) - Gives the same as above.