Legend:

• Green: Items - Sword and Shield
  
• Yellow: Star enemies paths (unkillable)
  
• Red: Blob enemies (killable)
  
• Blue: Doors, dotted line to the switch

First, get the sword (marked green, lower left corner of the map) and a shield (marked green, left side of the map).
- Recommend getting the shield first as it will give a health bar and allow absorbing some hits, also there are no blob enemies on the path there.
- When going for the sword, wait until star enemies pass and then run after them. Then grab the sword, wait for them to pass again and run back after them.
- Remember to hit the door switches on the way.

Now, with sword and shield you can kill blob enemies (marked red on the map). Keep in mind that even with the shield you have limited life and due to blob enemy positioning you are likely going to take quite a few hits by the end.

The room with two star enemies circling is annoying because they are out of sync. Generally, try to use the spacing to dodge them but there will be some (rare) unavoidable cases when they reach you together and you will get hit. Shield helps a little.

Remember to kill the enemies in the middle of the same room and hit the door switch to the treasure chamber and dragon.

Other than that it is very straightforward, follow the path down and then up, killing blob enemies on the way. As for the dragon - simply hit it with the sword. When it is dead, the door to the left will open for a shortcut back.

Pick up the crown from where the dragon was, then go back to and enter the castle.

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