Evidently, though this allowed him to be able to attack Lucius from that plane, that didn't stop Lucius from reacting to the act.
As soon as the attack manifested in the real world, he'd be able to react and use those eyes of his to dodge.
That's where the plane of madness became even more beneficial.
Within such a plane, time wasn't linear and completely warped in all directions in relation to the 'real' world so in simple words, Orion could attack Lucius from the past or future.
To be more accurate, he left seeds in past versions of Lucius that'd bloom in the present and form injuries which led to the fourth and final step of the technique.
Unfortunately, he couldn't trigger those seeds from the plane of madness so he was forced to come back in the real plane every time he wanted the injuries to bloom on Lucius.
This was [Mist], a technique he'd created on the fly.
