Friend of the Fey Quest
She will ask you for 1 set of beads, which can be obtained from an NPC jeweler, and a Jar of Honey, which can be gotten from an NPC baker. Once these items have been toggled as quest items and returned to Synaeva, she will give you the "Gift to Arielle" item and part II of the quest chain, the Gift to Arielle quest.
For the Gift to Arielle quest, go to Spirituality moongate in Ilshenar and seek out Arielle the Fey near the pool (i.e., where all of the pixies spawn and the unicorn, as well). She will accept your gift and give you a new quest called Alliance.
The Alliance quest requires you to kill 20 reapers and return to Arielle. Once the reapers, which can be found in abundance near the Justice moongate in Ilshenar, are slain and you returned to Arielle, she will give you Summon Fey as your reward.
Notes
Even if you are able to obtain the scroll elsewhere, you must complete this quest before you may cast it.