What you see here is a colored HP bar system for bosses. This would theoretically make boss HP easier to keep track of. These bars would sit at the bottom of the screen in a boss room.
The image above shows a boss taking damage from an attack, going from a fully purple HP gauge to a gauge that's partially red.
For dual-bosses and multi-bosses, the HP bars would be closely arranged with one another. For example...:
If one were to fight Cionic Organism and Moonchyllus at the same time, both of their HP bars would be displayed next to each other in the screen.
How are the names written in? Well...:
As shown here, the names are written in Samdan font, 24 points with a white fill and a 1-point (1 px) black outline. They are left-aligned and pt at the leftmost edge of the boss HP bars. SImple, right?
But yeah, this should help keep track of a boss' HP, especially when you wanna deal with those dang healing mechanics.
. I think it would be hard to kill even for 70-80 lvl.