Senior Enchanter Leorah is one of the newest Senior Enchanters in the Circle of Magi. She is in charge of the Circle's Laboratory.
She will sign your Rod of Fire request form for the Mage Origin quest Bound in Blood and Magic, if you clear the Infested Storerooms for her. Even if you get your form signed by alternative means, you can complete Leorah's quest for some spare potions she has handy.
It is likely that she became an abomination
or died defending the Tower
, as she is not seen during or after the events of the Broken Circle