“Oh, Doctor. Is anything wrong?” A young female nurse called out to an aged physician who had already finished his shift. They were walking in an inner ward of the hospital, slightly removed from the chaos.
“No; I just forgot something in a patient’s room.”
“Oh, I see. I hear the front entrance is a mess right now, so take care.”
“I will, thank you.”
The old doctor waited until he was certain the woman was gone. The next instant, his form had changed into that of the nurse who he had just been speaking to.
“How’s it going, Jack?”
The nurse’s — that is, the disguised Berserker’s — brain picked up a telepathic communication from his Master, Flat.
“No problems here. I have obtained a pass card to proceed deeper inside, so you can rest easy.”
Berserker had changed into the nurse completely, including the bar code-style card hanging around her neck. He continued further into the hospital, morphing into the people he passed in the halls and gathering information as he went.

Fate/Strange Fake: Volume 3, Chapter 9 ("Day 1, Evening")