The Corrupt Crown is one of the rarest mythical materials in Sailor Piece and a critical bottleneck for late-game progression. It only drops from one source — the Corrupted Knight boss on Boss Island — and the odds are not in your favor. If you're pushing toward Ascension 10 or trying to craft the Corrupted Excalibur, you'll need at least one of these, and possibly several.
Quick answer: Spend 1x Dark Grail, 650,000 Money, and 650 Gems at the Boss Summoner NPC on Boss Island to spawn the Corrupted Knight. Defeat it repeatedly until the Corrupt Crown drops at a 0.59% rate.
Corrupt Crown Drop Requirements and Spawn Cost
Before you can even attempt to get a Corrupt Crown, you need to collect Dark Grails. These drop from high-level mobs throughout the game and serve as the key summoning material for the Corrupted Knight. Each boss summon costs a fixed set of resources.
| Resource | Amount per Summon |
|---|---|
| Dark Grail | 1 |
| Money | 650,000 |
| Gems | 650 |
Once you hand these over to the Boss Summoner NPC on Boss Island, the Corrupted Knight spawns in the center of the arena. It has 750,000,000 HP, so you'll want a strong damage build before attempting this fight. The Corrupt Crown sits at roughly a 0.59% drop chance per kill, meaning you should expect to run this boss dozens of times — possibly more — before one appears.
Spawning and Defeating the Corrupted Knight
Step 1: Farm Dark Grails from high-level mobs. You'll burn through these quickly, so stockpile as many as you can before heading to Boss Island.
Step 2: Teleport to Boss Island and speak to the Boss Summoner NPC. Select the Corrupted Knight and confirm the summon using 1x Dark Grail, 650,000 Money, and 650 Gems.
Step 3: Fight the Corrupted Knight in the arena. The boss hits hard and has 750 million HP, so prioritize dealing as much damage as possible. Boss rewards in Sailor Piece scale with the damage you personally deal, which directly affects your chances of receiving rare drops like the Corrupt Crown.
Step 4: Repeat. With a 0.59% drop rate, there is no shortcut — you simply need to kill the Corrupted Knight over and over until the Corrupt Crown appears in your rewards.
Tips for Faster Corrupt Crown Farming
Running the Corrupted Knight on a private server is the single most impactful thing you can do. On public servers, other players can deal damage to your summoned boss, which dilutes your personal damage percentage and lowers your reward quality. A private server ensures 100% of the damage — and therefore the best possible reward scaling — stays with you or your group.
Grouping up with other players still helps, especially given the boss's massive HP pool. Just make sure your own damage output is high enough to earn strong rewards. A well-optimized damage build matters far more here than raw survivability, since faster kills mean more runs per session and a better statistical shot at the drop.
What the Corrupt Crown Is Used For
The Corrupt Crown feeds into two major late-game milestones. Both require significant additional materials beyond the crown itself.
| Use | Corrupt Crowns Needed | Other Key Materials |
|---|---|---|
| Corrupted Excalibur | 1 | Corrupt Tyrant Title, 25x Dark Grail, 15x Morgan Remnant, 8x Alter Essence, 3x Corruption Core |
| Ascension 10 | 3 | 2x Path Fragment |
The Corrupted Excalibur is one of the strongest fighting styles currently available, making it a top priority for endgame players. Ascension 10, meanwhile, requires three Corrupt Crowns — a steep ask given the drop rate. If you're chasing both, you'll need a minimum of four total Corrupt Crowns.
Trading for the Corrupt Crown
If repeated boss runs aren't producing results, player-to-player trading is an alternative path. The Sailor Piece Discord server is the most active hub for arranging trades. Expect the Corrupt Crown to command a high price — traders typically ask for multiple rare items in return, given how difficult the crown is to obtain. Trading won't save you from grinding entirely, but it lets you redirect your farming toward whatever the other player wants instead of relying purely on a 0.59% dice roll.
The Corrupt Crown grind is one of the most demanding material farms in Sailor Piece, but it gates some of the game's best rewards. Stack your Dark Grails, optimize your damage, lock down a private server, and settle in for the long haul. Every kill is another roll of the dice.