The Master Crown is the object Kirby unknowingly helped Magolor obtain by repairing the Lor Starcutter in Kirby's Return to Dream Land. Magolor used this to attempt to use its power to take over the entire universe, starting with Popstar. The crown was being guarded by Landia before it was stolen.
Appearance and Function
The crown takes on many shapes, though it is unknown what causes the change in appearance.
On Landia / On the ground
The crown is fairly small and could comfortably fit on the heads of any of the small characters in the game (Kirby included). It resembles a golden tiara with some small gems inset, though with small spikes protruding over the front that cover the forehead. Its power output at this stage appears to be low, but it is still enough that Landia is able to use its power to attack Kirby and friends.
On Magolor (after transforming)
The crown becomes a very large regal spire fit for a high king. Its gems grow larger and it is topped with many spherical towers, with the spikes on the bottom embedding into Magolor's head, making it resemble a claw holding his head. Power output is high in this form. Additionally, the crown will wobble on its own accord, implying it has a mind of its own.
On Magolor EX, the crown looks largely the same, though it bears a slightly altered color scheme.
On Magolor's second form
The top of the crown largely shrinks to a mere bauble, but the spikes grow to nightmarish proportions and serve as the supporting structure for Magolor's body. The magical capabilities of the crown in this phase are utterly dumbfounding, as illustrated by the attacks Magolor can perform.
In Magolor's soul form, the crown is even more ludicrously spiked, and bears a silver color scheme. As indicated by his Special Page, the crown is more-or-less in full control by this point, with Magolor being no more than a manifestation of the crown itself.
The origin of the Master Crown is unknown. However, Landia was tasked with its protection, having guarded it and the Lor Starcutter on Halcandra since ancient times. Landia wore the crown on its top head at all times, but rarely seemed to use its true power when fighting. This is likely because the crown itself has an evil will, and could easily corrupt anyone who taps into its power. As such, Landia's task seemed to be to specifically guard the crown, to prevent its use by anyone.
Magolor's primary goal during the story of Kirby's Return to Dream Land was to retrieve the crown from Landia, and he stole the Lor from Halcandra to try and achieve this goal. After his transformation, Kirby and friends battled him and destroyed the Master Crown. Magolor then returned to his original form, put his evil ambitions to rest, and even became friends with Kirby.
- It is possible that the Master Crown has ties to Dark Matter from previous games, as its incarnation as Magolor Soul possesses a huge red eye similar to that of Zero and 0².
- An item of similar function exists in the Fire Emblem universe, also known as the Master Crown. It similarly powers up its wearer, causing them to go up a rank, though this item is not evil or even self-aware.
- Void Termina can conjure several lasers using crowns that look like the Master Crown.