Finished that S Stages.
MVP: Ifrit. Handles the main lane, true AOE to hit the portal as well as all the mobs, and there were a ton of Ifrit lanes. ZT-S5 for instance, she can cover all the lanes.
Favourite Stage: ZT-S3. Really fun if you play with the mechanics and embrace the teleport. Plus bring Angelina + Gladiia + Cliffheart lets you cheese the 2 sides soooo much, even the really tanky guys with the reflection shield.
Overall, I really liked the event. Some of the enemies are really strong stat-wise, but the mechanic was fun to work with and overcomes the stat issue rather nicely.