The guide written below is going to be specifically for the Special Individual Interception version of the boss, however it does share mechanics with other versions in other game modes.
Modernia is the boss after Chatterbox in rotation of the week, if you are capable of clearing Chatterbox, then Modernia is only a slight step above that with a higher reliance on the beginning of the fight going well.
Update: They fixed the skip intro, you can now freely skip anytime and your characters will focus the core.
Once you are able to break the core, the rest of the fight really opens up.
Modernia will continuously go back and forth repeating the same attacks until either the other both wing breaks, you run out of time, or finish the fight by killing her.
Credits to A BBCCC for the low TP Kill and no healer.
Credits to Violet for a No Pilgrim unit clear ft Noise
Using Snow White as the Core Breaker, Ive swapped to Scarlet since the clears are way faster.