Just some quick tips for those who are having trouble with the event (myself I have done max points for reference.)
You don’t need to use the characters that give extra bonus, just go with your strongest DPS
You technically don’t need to use all the buffs, as you only need 20,000 points spread across all 7 bosses, so just mix and match boss buffs according to what teams you can work with. The ones that make the event the hardest that you might want to scale back are:
Don’t forget to use food and potions before the fight. Makes it a lot easier.
You can block the electro balls with Geo constructs (only tested with Ning’s screen, further testing required.) Alternatively if you dodge towards the ball as it lands you can i-frame it (but it’s a tight timeframe) or just Burst i-frame it as a safer alternative.
When the Electro Hypostatis goes into spinning laser beam mode, you can dash in and hit him during the duration
The last portion of the fight will require you to do elemental damage to several “energy cubes” in 3 locations (much like the World Boss.) You can 1 phase this by picking characters with quick E CD’s (like Bennett) or characters that can apply elemental status quickly (again, like Bennett with each of his E levels independently applying Pyro.)
If you fail and your characters die, just enter the event again, you get a full HP and Energy recharge before engaging the boss (you can also use this to heal during the event instead of statues, since the event has no power limit on healing unlike the statues.)