The Shadow Oracle clearly had no idea he had been found out. But even if he did, he had no idea he would find himself facing an existence that countered his nature in every aspect.
A shadow cannot be attacked by tangible weapons. A shadow is formless, so basically, it can be anything. So attacking a shadow is akin to attacking the air or the ground.
However, when Fury roared to life and flames gushed from his mouth, the Shadow Oracle found himself struck by a deadly soul attack, the kind that made him grit his teeth and materialize his body.
A shadow's fatal weakness is its soul.
The moment they become formless, their soul merges with them, so even the smallest soul attack would damage them. So an attack from the Soul Fury Forbidden Flame was surely enough to severely damage his soul.
COUGH!
