As a baseline example of how messy this can get, imagine playing Dark Depths and sacrificing it to, say, Crop Rotation
There are only four White cards that care about snow covered lands at all, but all of them hate or are hated by snow lands
The card's effect is that it simply stops the current game, use your current deck at the time as a deck for a new game
Voltron in Golgari is pretty unheard of, making Yargle and Multani a unique commander for if you want to try something outside of the usual black/green style
It needs to introduce the themes of the game, but still be wide enough for experimentation
Champion of the Perished , meanwhile, is a smaller Zombie that gets bigger as friendly Zombies enter the battlefield, and is worth $3.99