Sometimes people mix up the words “illusion” and “allusion.”
An allusion is an implied or indirect reference or a hint. Allusion is a device often used in literature to tell about something without specifically mentioning it. I used this device in the Tip Title today, obliquely making a pun using the lyrics of a Styx song. But now I’m not alluding to it, because I referred to it directly. Hence, use “refer” for direct mentions, and “allude” for indirect mentions.
Illusion is tricking, deceiving, or fooling somebody into thinking something is real when it’s not. Magicians often excel in the art of illusion, giving the false impression that something disappeared, when it was actually your attention that was diverted elsewhere.