After saving Darling, enter Combat Mode with a Dragon and Return to Stealth
This trophy can only be earned after you have liberated the first Garrison and rescued Dr Darling, which is the end of the second mission. To enter Combat Mode with a Dragon, either run right up to him to enrage him, or simply shoot him. The neon lights on his body will turn bright red, indicating Combat Mode. You must now return the Dragon to its blue neon lighting, which is Stealth Mode.

To do this, throw a Cyber-Heart away from the Dragon, and crouch behind some cover. The Dragons attention will be diverted away from you, and will forget about you. As soon as the lights on his body turn back to blue, this trophy will unlock.