The Last Ninja/The Palace

Starting on this stage, all enemies respawn as soon as you re-enter a given room.

You can now safely enter the palace. Proceed forward a few screens. When you reach the door, collect the apple at the bottom-right corner, and equip the key. Enter the doors using the key.

Once you enter, defeat the guards, and proceed southeast until you reach a statue. There are two ways past it, the easiest is to try passing the statue as close as possible. Once you get past it, head northeast, and search the gray urn in the north-east corner of the room. This provides magic that allows you to get past the stairs.

Return south, and continue south east to the staircase. Defeat the guard and run up the stairs.