Not much on that because its just a participation trophy of doing the equivalent of a elite world quest solo. When you get the 1st clearing it achieve + all the achieves up to 5 mask clearing it, it proves you bought a boost. You can not get your first mask until you full clear it for the first time.
I was just ranting about people buying boosts and touting their achieves in an attempt to showcase a level of skill they have don’t actually have. Think of someone buying a 2k boost and then creating a group in lfg saying 2k+ only when before they bought the 2k they didn’t have the stepping into arena.
Edit: are you asking about just the simple full clear achieve or 5 mask full clear achieve?