As Mrs. Teasdale mentions, she and Coil first did this trick in the middle of our 28th storyline, "This Mortal Coil." As for Howlett's little chant, we've heard it three times before in the comic, most recently during the confrontation with the Nulla Lucis near the end of our 24th storyline, "A Long, Long Trail A-Winding." It always heralds the appearance of another character, so I'm expecting him to show up in next week's conclusion to "Adagietto." Stay tuned!
Fifty - Adagietto