First, you need to beat the game.
Make sure you have a save file for Chapter 15
(maybe several wouldn’t be a bad idea).
- Load your Chapter 15 save after beating the game.
- Kill Ifrit again, and enter the throne room.
- Warp from the throne room down to Ardyn.
- Warp repeatedly to reach the building balcony.
- Warp to the Magitek Engine situated near the invisible wall.
- Warp to the tree to go to the balcony again.
- Turn left at the end of the balcony, and head east.
- Turn left and go north at the wall you see.
- Jump over the rubble.
- When you wind up on the street, run to the sleeping lodge.
- Open the lodge door.
- Fight Ardyn around this area until he has about 3/4ths of his
health – when he starts using magic, and won’t warp away.
- Press “X,” and wait for Ardyn’s attacks to end.
- Select “No,” and attack Ardyn repeatedly.
- Press X again after you’ve done some major damage.
- Repeat these steps until the cutscene starts.
- Wait for the cutscene to end, and until Armiger starts.
- Select “Yes” when the floating swords appear.
- Go through with resting.
- Move up above Insomnia.
- Load your latest quick save.
- Save your file.
- Use Umbra to go to Altissia.
- Ride the gondola to make the menu work again.
- Save a final “God Mode” save.