Makarov dies in chapter 505 to save his irreplaceable children. Now, in chapter 506, Natsu goes to the Guild and possibly faces August or Eileen.
In chapter 505 of "Fairy Tail," Natsu, a Mage of the Fairy Tail Guild, was forced by Gray – the Ice-Maker Mage – to reveal his true identity as the creation of his brother – Zeref Dragneel. Gray believes that Natsu is the Etherious Natsu Dragneel or E.N.D. Refusing to reveal his true identity, Natsu continued to fight Gray in the war instead of teaming up against the darkness.
Makarov Dreyar, a Master of the Fairy Tail Guild, makes a decision to use the Fairy Law – one of the three great Fairy Magics that releases a bright light that will harm the user's enemies but leaves others unharmed – to stop the war between Natsu and Gray.
One of the first Guild Masters — Mavis — tried to stop Makarov from casting the Fairy Law because she knows that the magic will consume Makarov's life. But Makarov has made his final decision because he wants to protect his "irreplaceable children" while eliminating the army that Eileen created from her Berserker Enchant magic.
Makarov succeeds in casting the Fairy Law, at a great loss to the Fairy Tail Guild.
Movie News Guide reports that in the chapter 506 of "Fairy Tail," Mavis will be avenging Makarov's death and she will be going against Eileen herself. Everyone will be brought to their senses, including Natsu and Gray who are fighting instead of working together to stop the war.
But according to The Bitbag, the two will continue their fight until Natsu is finally able to defeat Gray. He will then come to the Guild and he will face either Eileen or August.
However, once Natsu and Gray find out that Makarov is gone, the two will team up to take care of the remaining Spriggans at the Guild.
