Greetings, this would be my first plugin request so if it seems somewhat impossible please just say so... I'm quite un-knowing to how Java works, I have yet to read up on it. The Looking "Glass" would be a specific command, /lookingglass. This would use Obsidian, and Glass (obviously.) Once you (have the proper permissions to do so, you can) place an obsidian block, whilst the /lookingglass command is toggled ON. When on, the obsidian block will be special from all other obsidian blocks, in that you are placing one of the "Looking Glass" pieces. If you rightclick the block (similar to how you right-click a rune in Runecraft), it will turn into Glass. No other blocks will do this, which is why the specific block of obsidian placed is special. You can do this repeatedly, as the block is toggled between glass and obsidian. The only people who can destroy this are the admins, moderators, and/or any other special ranks + the person who placed it... or whomever you choose, but those are the recommended criteria. Thank you.