Hello! I wrote a simple plugin for a custom event, CommandBlockChangeEvent. The plugin uses ProtocolLib. Now you can simply detect if a player changes a commandblock and/or change the command or even cancel the change. Example: Code: @EventHandler public void oncbc(CommandBlockChangeEvent e) { String command = e.getCommand(); if (command.startsWith("tp")) e.setCommand("tp @p @p"); // Trolling =P if (command.equals("help")) e.setCancelled(true); } Download