Ars Goetia.

The key in Arcadius's chest dissolved, returning to its natural state — a flame.

Then, the waves of energy that he'd been emitting magnified and clashed against Berkah's in a scene that resembled two magnetic fields visibly repelling one another.

And...

Crack! Crack!

Before Berkah's very eyes, Arcadius's bone structure began deconstructing as though there was someone trapped inside of his body and wanted to break free.

BOOOOOOOOOOM!

A great inferno suddenly sprang forth and encased Arcadius, forming something of a barrier like sepals made from condensed flame.

[This looks familiar...]

Berkah tilted his head pensively.

CRACK!

A loud sound brought him back to reality and he saw that the flame rampart had taken the form of a dewdrop, or rather, a flower that was yet to bloom.

CRACK! FLARE!