Gray and the others surprise Lucy when they welcome her to her own apartment, with Erza telling them they have to stick together in case anyone gets attacked. However, this has already happened to the members of Team Shadow Gear, Levy McGarden, Jet, and Droy, who were attacked and pinned to a tree.  Gray attacks Phantom Lord alongside most of Fairy Tail, but they are forced to retreat when Makarov loses his Magic Power because of Aria, leader of the team Element 4 of the Phantom Lord guild. 
Juvia takes this the wrong way and believes that Lucy is Gray’s girlfriend
Back at the guild, Gray and the others are surprised at the revelation of Lucy’s history and comfort her while she is depressed.  Just then, they feel the guild quaking and rush outside to see what the commotion is: the Phantom Lord Guild is literally walking towards them on six legs.  It attacks with its magical Convergent Cannon: Jupiter, but Erza narrowly stops the powerful bullet from obliterating the guild, rendering her incapable to fight. Jose Porla calls out, demanding that they gave Lucy to him, but receives an adamant refusal. In response, he tells them to quiver for 15 minutes as Jupiter reloads. Rather than wait to be destroyed, Gray and Elfman follow Natsu and Happy to destroy the cannon before it can fire again. 
After the cannon is successfully decommissioned, Jose orders the guild to enter a more powerful form: Super Mage Giant Phantom MK II. Gray and Elfman arrive just in time to save the motion-sick Natsu from Totomaru, one of the members of the Element 4. Happy flies outside to see what’s going on, and returns to tell them that the guild has become a gigantic Mage that is beginning to cast a spell called Abyss Break, which would destroy half of Magnolia. They then decide to split up to find the moving guild’s power source. 
Gray goes to the roof and, noticing that it is raining, wonders whether it was raining before. He is approached by Juvia Lockser, one of the Element 4, who shows an immediate romantic attraction to him. She begins by declaring her loss to him and starts to leave. However, she changes her mind and attacks Gray with her Water Lock. He quickly freezes his way out, but not without opening his wound ,which he obtained from his battle with Lyon, in the process. Gray strips as usual, causing Juvia to think that their relationship is going too fast. Gray then uses his Ice-Make: Lance on her, but is surprised that the attack goes right through her torso without damaging her. As she tries to convince Gray to stop and hand over Lucy, Gray announces that he’ll never give up a comrade, even if it results in his death. 
She then gets angry at Lucy, confusing Gray, and attacks him with boiling water. He tries to freeze her water and succeeds, but accidentally grabs Juvia’s breast in the process. She then tries to confess her love for him, but he mentions how the rain is depressing before she can say it. This sends Juvia into a rage and she attacks him again, but Gray prevails and defeats her, stopping the rain around her in the process. 
He quickly lets go and apologizes to her, which surprises her
Later, he tries to fight the Phantom Lord master alongside Erza, these details Elfman and Mirajane, but given their already weakened states, Elfman, Gray and Mirajane are easily defeated while Erza tries to fight alone.  Makarov then reappears and tells Erza to leave and take Gray, Elfman and Mirajane so he can fight Jose without worrying about his surroundings.