I originally did not consider writing a comment on the final duel,

but after experience it is clear that many players still do not know what is "appropriate"

The final fight can be divided into 4 phases

1st phase  RED 
Boss Lv 20 -> Lv 15

Immediately upon entering the arena, activate the red energy pillar.

note: When the boss is supplied with red energy you deal him many times more damage over time!

2nd phase  BLUE 
Boss Lv 15 -> about Lv 12-13

Three stages in total
Destroy the boss's most radiant minion  (who is trying to transfer energy to him)
At the same time, destroy  all pyramids 

After destroying the last (3) most radiant minion...

another wave of  pyramids will follow, as well as  traps (smaller double-sided pyramids) -> destroy everything!

note: if you are not attacking the boss, but his assistants or other objects, it is advisable to weaken the boss's attack power  BLUE 

P.S. It is completely pointless to attack the boss's minions, which emit a small glow. 

3rd phase   RED 
Boss about Lv 12-13 -> Lv 4

After destroying the second wave of pyramids, switch to  RED  energy to damage the boss as much and quickly as possible.

If you have destroyed everything under blue energy, nothing will bother you except the boss until Lv 4
However, be careful around the boss, and free those who are trapped (if all traps have not been destroyed).

4rd phase  RED 
Boss about Lv 4 -> Lv 0

From Lv 4 onwards, the boss's minions and traps appear around him again, either destroy them or avoid them.

And keep attacking the boss with full force.

If you are in close proximity to the boss's pillar, your damage will be lower

(usually there is no colored warning on the ground about subsequent damage).

note: if you have enough time, you can consider switching to  YELLOW  or  BLUE  energy,

I don't do that, I can usually survive until the boss is defeated.

P.S. I think there are different minions in the final stage with different properties depending on the color of the energy... be careful!