If you are guild level 50 or above, this will cost you a life. (You will be warned and asked if you want to continue if this is the case.) Otherwise, it will only cost you all of your guild and social points, and some constitution--or, if you are young enough, nothing.
Calling the godmother
You can summon her with the syntax "godmother help". After she arrives, you can "say yes" or "nod" or "think yes" to confirm that you want her help. The non-verbal methods are especially useful when underwater or otherwise unable to speak.
After transporting you she will take a life if your guild level is 50 or above.
The godmother that appears is an unnamed fairy godmother. Magrat Garlick was said to sometimes appear as the fairy godmother, but this doesn't seem to happen anymore.
a fairy godmother This fairy godmother isn't quite what you expected. She is tall and forbidding; not in the slightest bit cuddly or smiley. She looks slightly uncomfortable and is currently glaring at her wand, which appears to be malfunctioning. If you cross her, you might find yourself turned into a wombat or worse. She is in good shape. She is standing. You can't help but notice thirty warts upon her face. Holding : a godmother wand (left hand). Wearing : a pair of hobnailed boots, a black witch's cloak and a witch's pointy hat.
a fairy godmother In the realm of Fairy Godmothers, this one must certainly take honours in a Division Yet To Be Announced. Grimly determined to do things properly, she has woven wild flowers in her windswept, golden locks, powdered her face to a fashionable pallor and has attired herself in numerous fluttering shawls, bangles, and a vivid green gown. The overall effect is that of a maypole with a flower box emptied over its head that happens to jingle like a tinker's wagon with a broken wheel. With one hand she clutches her regulation wand and with the other she dabs at her red and dripping nose with a damp scrap of lace. She is in good shape. She is standing. You can't help but notice twenty warts upon her face. Holding : a godmother wand (left hand). Wearing : a pair of black pumps, a startling green dress and a black lace shawl with spiderweb motif.
Godmothering when dead
If you are dead and call on the godmother, she will raise you from the dead as well as transporting you. She will also bring your corpse along, if it's in the room. Then she will take a life if your guild level is 50 or above.
Godmothering from broken rooms
The godmother will help you for free if you're in limbo or somewhere the exits have disappeared, even if she would normally charge you a life. (Note that no obvious exits is not the same as no exits.) If you're told that it will cost you a life, it will. If you feel the room is bugged but the godmother says she will take a life it is best to try to talk to a liaison.
Attacking a godmother leads to a curse, and a temporary ban from godmother services:
The fairy godmother says: What is this travesty! Attacking your fairy godmother, Well I never. The fairy godmother exclaims: Unsup Ported I here by curse you! The fairy godmother says: Don't expect me to help you again.
Then "godmother help" only produces the following message: "You attacked a godmother! No help for you!".