9x4 - Fairy Tail

Natsu, Lucy, and Happy use Virgo's tunneling magic to infiltrate Avatar's base. When Natsu alerts Avatar to their presence by calling out to Gray, they encounter three of the cult's elite black wizards, whom Natsu quickly defeats before Gray arrives and attacks him. Natsu implores Gray to rejoin Fairy Tail, thinking he is possessed, but Gray refuses and says that he has joined Avatar of his own volition. The cultists capture the trio before leaving to carry out their "purification" plan, which involves a ritualistic massacre of innocents in an attempt to summon Zeref. One of the cultists, Gomon, stays behind to torture and interrogate the trio, but Gray freezes him and releases his friends, revealing that he has been secretly working undercover together with Erza Scarlet.