If you're in a Devoid colored deck, it's still super useful since you'll still heavily be invested in cards that need colorless sources
He also brings a competitive aspect to the game buffing your in-play Princess characters
For Fun These precons did exceptionally well in this category, but Im going with Miracle Worker here
You can verify things, like centering, corner sharpness, check for scratches in the holo, etc
On top of giving near immunity to counters, red and black have a ton of creature and artifact removal effects, and with Shadow giving them split second, you can get around most tricks that other colors can use to protect their permanents
Choosing the right leader is an essential aspect of building a successful deck