Faralda is an advanced Mage of the College of Winterhold. She is the guardian who initially stops prospective students and requires them to cast a spell as a demonstration of their abilities. She specializes in teaching the school of Destruction, and starts the quest to obtain the most powerful Destruction spells once you reach 95 skill. Once that quest is complete, she sells the most advanced Destruction spells in the game.
Before entering the College, she requires the player to complete a test by a casting a spell. The player can use persuasion or reveal that he or she is Dragonborn to avoid the test, but the it may be advantageous to take it. Faralda will randomly choose a spell for the player to cast, and if the player does not have the spell, she will sell it for only 30 gold. Possible test spells are Heal Other, Magelight, Conjure Flame Atronach, Fear, and Firebolt.