After defeating the weak form of Anankos, he devastates Valla and attacks in dragon form.
Before the Battle
Optimize everyone's inventory before you start the battle.
Defeat the Boss
After you start the battle, advanced level 20 enemies will appear in a circle around your units.
To kill Anankos, you first have to kill his hands, so you will need to split your units into two groups, one to the west and one to the east.
After you have killed both of Anankos's hands, you can start attacking its head. As before, the Omega Yato will do a lot of damage, as will the other legendary weapons that contributed to the Omega Yato (Xander's Siegfried, Ryoma's Raijinto, Leo's Brynhildr, and Takumi's Fujin Yumi).
Finally, when you have killed Anankos's head, its orb will come out and you will have to kill it. After you do, you have won the game. Congratulations! After the credits, when it says The End, press A and you will be prompted to turn five of your units into Einherjar units, which you can purchase from the Einherjar Shop in your castle (if you build it), allowing you to use those units in battle.