As part of the Part 1 Improv-Singularity Repair Support 4 update, there have been changes to the Christmas in the Underworld Main Interlude and the inclusion of new “Advanced Quests”.
Just like the previous Prison Tower, Christmas in the Underworld is now free and only requires completion of Babylonia. Any Rare Prisms spent on the event will be refunded. Rare Prisms will still be needed to purchase further NP copies of Santa Altera. To commemorate this update, there is a Christmas in the Underworld Banner featuring Ereshkigal, Ishtar, and the Christmas Event CE’s.
Christmas in the Underworld Banner
Advanced Quests are a new type of Quests that are permanently added to the Chaldea Gate after meeting some requirement and will reward a unique CE upon completion. No Support Servants can be used in an Advanced Quest and they can not be repeated.
The first Advanced Quest requires London completed and rewards a CE that increases Void Dust drop rate by a multiplicative 5%. Also from the 26th to Feb 2nd, free quests will cost 1/2 AP until completion of 1st time clears for players who have cleared Babylonia and any dust drops will be twice as many.
This Advanced Quest is against Robin, Proto Cu, and Saber Lily and the gimmick is that it further increases the ATK and DEF multipliers when using full class advantage. Sabers will do even more damage to and take even less damage from Lancers etc. Berserkers and Pretenders do not benefit from the gimmick.
Advanced Quest page
Part 1 Improv-Singularity Repair Support 4 page