I must also say that the store itself is fun to look around
Thousands of fake Tarmogoyfs, Windswept Heaths, and Jaces are probably out there already
The play pattern here is to get Vivi in play, pitch a huge red spell card to cast a free Blazing Shoal and make Vivi enormous, then use Vivi's ability to generate loads of free mana and cast more giant spells, storm off, or simply swing and deal heaps of damage to your opponent with the now embiggened mage
For instance, if I have a 3/3 creature, I can put as many +1/+1 counters on it as I want (although once its power is equal to the opponent's life total, the value gained drops off quickly)
Every year, Magic: The Gathering releases more cards than any one person could reasonably keep up with
Given that he is one of just five Eminence Commanders in Magic and that this ability is among the most powerful the game has ever seen, it becomes pretty obvious why he is so beloved