Chapters: 10-23, Episodes: 5-10

!! Short Summary
Erza Scarlet is introduced and enlists the aid of Natsu, [[AnIcePerson Gr]][[TheRival ay]] and Lucy to stop a dark guild from dropping a FantasticNuke.

!! Main Summary

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''Lullaby Arc'' has the following tropes:

* AnIcePerson: The formal introduction of Gray, [[EarlyBirdCameo who first appears in the Introduction Arc.]]
* AttackOfTheFiftyFootWhatever: The Lullaby turns about to be sentient and when Kageyama is convinced not to play it by Makarov it decides to show it's true form as a giant monster.
* BigBad: Erigor, who is also a DiscOneFinalBoss.
* BrownNote: Lullaby, said to be able to kill anyone who hears it.
* CastingAShadow: Kageyama's power which allows him to use shadow powers to his whimes.
* HeelFaceTurn: Virgo upon coming into Lucy's possession when it's revealed she was just acting on Everlue's orders in the last arc. Not only does her allegiance change, [[VoluntaryShapeshifting but so does her appearance.]] Kageyama also has one after talking to Makarov.
* LadyOfWar: Introduction of Erza.
* LuredIntoATrap: After Erigor finds out that some of the Fairy Tail guild have found out what they're up to, he conconts a plan to apparently broadcast the flute at a train station which the Fairies follow his group into. It turns out it was a feint as Erigor surrounds the building in a wind wall to trap them there while he goes to his real target, the meeting of the guild masters in a neighboring town.
* NiceJobBreakingItHero: Our heroes defeat the Lullaby monster and save the guild masters...but also accidentally knock said monster into their meeting hall.
* OneWingedAngel: Lullaby itself.
* RazorWind: Erigor main power which allows him to control wind and uses it to cut up targets.
* UngratefulBastard: Kageyama, at least before he meets Marakov.