Apollo stepped partially into the shadow world, finding his breath caught in his throat.
He tried to manually step out, but ended up stumbling once he reappeared in the real world.
However, Apollo had essentially gotten the essence of the technique down. In fact, he wouldn't mind if the man of black mist disappeared. After all, the principles of this technique were what the man of black mist displayed.
And Apollo had already understood the principles. He just needed to iron out the edges. So that's what he did.
Apollo pushed off the ground, before partially entering the shadow world. This time, he preemptively held his breath and simply remained still.
Less than a second later, he reappeared in the real world while his foot landed on the stone platform with a clear tap.
He had successfully completed the technique.