If you can think of a noob mistake that a little kid could make (running 60 card decks, prioritizing Life Points too heavily, or running cards that are too hard to use), then the chances are I've probably done that when I was that young
I was very eager to find a way to make a Squirrel lord
It takes 2 Dark & 2 Colorless, but it does a whopping 120 damage, with the side effect that you have to discard the top 3 cards of your deck
Despite their more fiendish design, these cards didn't catch on like the regular god cards
To create these bright colours, the so-called WUP (White Underpainting Layer) is used, an extra layer of white ink is applied to the areas of the card that need to have brilliant colours and not appear shiny
That said, it would be nice to see different cards slide into the future reprints