"You shall not pass... up this incredible costume!" - Gandalf, mostly. We may have fudged some of it.
Wizards are pretty incredible, aren't they? They can do some seriously powerful magic and somehow look good doing it. After all, who else is going to pull off sparkly purple robes other than a wizard? Cher? Maybe. Maybe Cher on a good day. But mostly it's just wizards. And those beards! How is a long white beard on a wizard always so becoming? Can you picture a clean shaven man pulling off incredible magic with the flick of their wrist? No, because that's just absurd. Maybe their power is hidden in their beards, like Samson. Maybe it's from all the conditioner they need to use. We just don't know. What we do know is that if you upset one of these wizards you'll be turned into a frog in the blink of an eye. That's how incredible these wizards are.
Like, was there ever a time when Dumbledore didn't impress you? No! Of course not, don't be ridiculous. He's freaking Dumbledore. The guy could conjure a circus out of thin air and he wouldn't even break a sweat. Dumbledore fighting Gandalf would probably cause the earth to explode. Dumbledore and Gandalf fighting together though? We're pretty sure Sauron and Voldemort would be crying in a corner together. Which is why this costume is so important. Wear this, get the beard rocking and wave your wand. The world needs you, young wizard! And with all that cosmic power at your fingertips, anything is possible.