Make the HoH live up to its namesake. Have the three star one simply be a small hall with the statues of the original alpha squad with npcs standing around to tell their stories. At the end basil will be there with every recipie in the game up to three stars. You will be able to buy one (or receive one) of choice much like how you can only get mission prestige once. You get your award and take the elevator up to the empty slot in the right of the arcade.

In the four star one it will be similar but also contain statues of the GMs and bosses. The npcs who were now standing in front of alpha squid will be in front of the new statues. There will also be construction in alcoves. As before you will get/buy one recipie before returning to haven.

Some quick notes,
one) the whole area will be in a mine.
Two) if you do not buy the recipie/accept one you can return and get it. Once you hit accept it will be sent to you in the mail once you finish the mission.
Three) you can return and look at the recipie list but not buy.

Finally the five star and final one. The five star will be a massive maze of hallways With statues of every knight who has received vanguard status up to that point. In order to protect the servers it will only update with major patch updates. In the final one you have a statue in a place of honor in the dead center. You will not get a recipie but will be able to view all recipie including SL ones.

Also in the final hall you will receive one bound confetti of each type :)