The Castle Entrance is unlocked when you complete The Forest. It contains Knights which have 150 HP each. The easiest ways to get through are to get A Magical Sponge and use "squeeze" to go under the guards, or to use the Rocket Boots to jump over the castle wall.
After successfully completing this quest, you can move on to The Castle.
Tip[edit | edit source]
With the Boots of Introspection stand just past the entrance and kill enemies for 2000 candies per kill.
Or you can use the Boots of Introspection to remain where you spawned and use the Black demons spell acquired via the Black magic grimoire to greatly increase the amount of candies earned. Using this spell is most effective when standing to the far left. Combine with Candy Merchant's Hat to increase effectiveness even more.
Another tip is with the pink gloves and a powerful weapon, this can be the fastest and most effective way of earning candies.