Plague Doctor

Colin heard the door open and the rustle of a long coat. Another doctor, he assumed. He didn't look up.

"How's the book?"

"It's really interesting!" Colin enthused. "The body is kind of like Starcraft. There's a build order and all different kinds of units, like B cells that spit out disabling shots and T cells that build killer T cells that track and destroy and phages that are almost like mercenaries..." He trailed off as he registered the black coat, the wide-brimmed hat, the bird mask.

The figure leaned forward. "Kekeke," it said, in a deep voice, "Zerg rush."

For reference.