diff --git a/database/sql/1-db_database.sql b/database/sql/1-db_database.sql
index 1d381f546c..c24fc76912 100644
--- a/database/sql/1-db_database.sql
+++ b/database/sql/1-db_database.sql
@@ -15978,9 +15978,11 @@ CREATE TABLE IF NOT EXISTS `medalmaps` (
 ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;
 
 CREATE TABLE IF NOT EXISTS `monsterbook` (
-  `charid` int(11) unsigned NOT NULL,
+  `charid` int(11) NOT NULL,
   `cardid` int(11) NOT NULL,
-  `level` int(1) DEFAULT '1'
+  `level` int(1) NOT NULL DEFAULT '1',
+  PRIMARY KEY (`charid`, `cardid`),
+  CONSTRAINT `FK_monsterbook_characters` FOREIGN KEY (`charid`) REFERENCES `characters`(`id`) ON UPDATE CASCADE ON DELETE CASCADE
 ) ENGINE=InnoDB DEFAULT CHARSET=latin1;
 
 CREATE TABLE IF NOT EXISTS `monstercarddata` (
diff --git a/database/sql/migration/monsterbook.sql b/database/sql/migration/monsterbook.sql
new file mode 100644
index 0000000000..be886cb925
--- /dev/null
+++ b/database/sql/migration/monsterbook.sql
@@ -0,0 +1,4 @@
+ALTER TABLE cosmic.`monsterbook`
+CHANGE COLUMN `charid` `charid` INT(11) NOT NULL,
+ADD PRIMARY KEY (`charid`, `cardid`),
+ADD CONSTRAINT `FK_monsterbook_1` FOREIGN KEY (`charid`) REFERENCES `characters` (`id`) ON UPDATE CASCADE ON DELETE CASCADE;
\ No newline at end of file
diff --git a/src/main/java/client/Character.java b/src/main/java/client/Character.java
index 14437d463a..284e5abdc8 100644
--- a/src/main/java/client/Character.java
+++ b/src/main/java/client/Character.java
@@ -8464,7 +8464,7 @@ public class Character extends AbstractCharacterObject {
                         ps.setInt(i + 31, getSlots(i));
                     }
 
-                    monsterbook.saveCards(getId());
+                    monsterbook.saveCards(con, id);
 
                     ps.setInt(36, bookCover);
                     ps.setInt(37, vanquisherStage);
diff --git a/src/main/java/client/MonsterBook.java b/src/main/java/client/MonsterBook.java
index 1919fb344c..d354ab84e7 100644
--- a/src/main/java/client/MonsterBook.java
+++ b/src/main/java/client/MonsterBook.java
@@ -32,12 +32,9 @@ import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.util.*;
 import java.util.Map.Entry;
-import java.util.concurrent.Semaphore;
 import java.util.concurrent.locks.Lock;
 
 public final class MonsterBook {
-    private static final Semaphore semaphore = new Semaphore(10);
-
     private int specialCard = 0;
     private int normalCard = 0;
     private int bookLevel = 1;
@@ -180,61 +177,27 @@ public final class MonsterBook {
         calculateLevel();
     }
 
-    private static int saveStringConcat(char[] data, int pos, Integer i) {
-        return saveStringConcat(data, pos, i.toString());
-    }
+    public void saveCards(Connection con, int chrId) throws SQLException {
+        final String query = """
+                INSERT INTO monsterbook (charid, cardid, level)
+                VALUES (?, ?, ?)
+                ON DUPLICATE KEY UPDATE level = ?;
+                """;
+        try (final PreparedStatement ps = con.prepareStatement(query)) {
+            for (Map.Entry<Integer, Integer> cardAndLevel : cards.entrySet()) {
+                final int card = cardAndLevel.getKey();
+                final int level = cardAndLevel.getValue();
+                // insert
+                ps.setInt(1, chrId);
+                ps.setInt(2, card);
+                ps.setInt(3, level);
 
-    private static int saveStringConcat(char[] data, int pos, String s) {
-        int len = s.length();
-        for (int j = 0; j < len; j++) {
-            data[pos + j] = s.charAt(j);
-        }
+                // update
+                ps.setInt(4, level);
 
-        return pos + len;
-    }
-
-    private static String getSaveString(Integer charid, Set<Entry<Integer, Integer>> cardSet) {
-        semaphore.acquireUninterruptibly();
-        try {
-            char[] save = new char[400000]; // 500 * 10 * 10 * 8
-            int i = 0;
-
-            i = saveStringConcat(save, i, "INSERT INTO monsterbook VALUES ");
-
-            for (Entry<Integer, Integer> all : cardSet) {   // assuming maxsize 500 unique cards
-                i = saveStringConcat(save, i, "(");
-                i = saveStringConcat(save, i, charid);  //10 chars
-                i = saveStringConcat(save, i, ", ");
-                i = saveStringConcat(save, i, all.getKey());  //10 chars
-                i = saveStringConcat(save, i, ", ");
-                i = saveStringConcat(save, i, all.getValue());  //1 char due to being 0 ~ 5
-                i = saveStringConcat(save, i, "),");
+                ps.addBatch();
             }
-
-            return new String(save, 0, i - 1);
-        } finally {
-            semaphore.release();
-        }
-    }
-
-    public void saveCards(final int charid) {
-        Set<Entry<Integer, Integer>> cardSet = getCardSet();
-
-        if (cardSet.isEmpty()) {
-            return;
-        }
-
-        try (Connection con = DatabaseConnection.getConnection()) {
-            try (PreparedStatement ps = con.prepareStatement("DELETE FROM monsterbook WHERE charid = ?")) {
-                ps.setInt(1, charid);
-                ps.executeUpdate();
-            }
-
-            try (PreparedStatement ps = con.prepareStatement(getSaveString(charid, cardSet))) {
-                ps.executeUpdate();
-            }
-        } catch (SQLException e) {
-            e.printStackTrace();
+            ps.executeBatch();
         }
     }