Seeing the opponent charge in a straight line wearing "Portal Armor," I first unleashed a vast wave of flames at him.
We were both high in the sky, and he was below me; the massive wave of flame resembled a torrential downpour intended to overwhelm a mosquito flying upwards. Yet, the reality was contrary to the scene observed. The black "mosquito" was not only unaffected by the fiery red "water," but it charged up as if in an invulnerable state.
Sure enough, this level of attack was ineffective against him now.
If I wasn't mistaken, his ability to manipulate shadows was of the same nature as the Shadow Manipulation used by the weirdos I had encountered in the past.
At the beginning of the fight, his ability to suddenly disappear must have been Shadow Transfer. He likely dove at high speed into the shadow below him and then leaped out from the shadow behind me.