There is a nasty rumor going round about wizards and succubi. Allow me to set the record straight: it is mostly true. The succubus, plural succubi, is a female demon of great and surpassing naughtiness. The males of their type, being type 69, are called incubi. Wizards are rumored to consort with spirits and demons for diverse purposes and succubi for other diverse purposes.
Understand that all demons are spirits and manifest on this plane in material forms of expectation. All demons are unconscious mind-readers. That is to say that they do not know they are mind-readers. When they manifest their unconscious minds make a connection to the unconscious mind of the summoner and the form they assume is shaped by the unconscious expectation of the summoner himself. In times long past early demonologists wrote down their rituals and described the results of their efforts, sometimes with sketches. As a result there is a general idea already in the summoner's mind of the demon's form. For this reason demons generally appear in the same forms once identified.
Succubi, on the other hand, have a more complicated form of mind reading. Succubi appear as the summoner DESIRES they appear. So exact is this ability that the succubus appears as the summoner TRULY desires. Thus a wizard well into a ritual, dealing with a raging erection, might be quite surprised by what arrives.
Naughty. Hell tart.
One wizard of my acquaintance found his summoned demon to be an incubus. Of those that know him none were surprised save himself.
The moral of this story, if indeed there is one, is DO NOT summon a succubus into a location where observation might cause you embarrassment and social awkwardness.
On a related note, I should tell you that summoning a demon is like inviting a guest to your house. Once they've been there they always know where you live and might drop by unannounced. In the case of succubi this can be most annoying. One minute you are snoozing away having a lovely dream about fishing and the next some naked temptress is shaking her moneymaker in your face and making double entendre about your "pole" and "worms".
You have been warned.