"What have you done with Dick Grayson?" Batman demanded. The impostor in the dark suit said nothing. Actually, his actions spoke loud enough.
Wasting no time, he lunged at the Batman and forced the crimefighter backwards onto the ground. The two masked men grappled with each other for several minutes, rolling across the office floor in a single mass.
As they tussled, Batman grew acutely aware of his own vulnerability. The lengthy span since the onset of his illness had left him badly out of shape (at least by his usual standards--though he was still unspeakably more powerful than the average citizen).
Even so, Batman knew he could not afford to be defeated, and after an extended and agonizing battle he subdued his attacker at last. Once he had the upper hand, he pinned the other man to the floor, immobilizing the Impostor by planting the full weight of his body over the man's torso and pressing every available limb firmly into the ground.
"This ends right here, right now, Strange," Batman barked, as he reached for the mask on the Impostor's face and yanked it off.
What he saw beneath the mask struck him with a force more powerful than any blow.