You see, Emiel also has an ability that allows you to pay one White or Green mana to put a +1/+1 counter on your Creatures that enter the battlefield
For the most part, building the best deck will involve selecting one of these existing strategies and instead focusing on optimizing the counts of various supporting cards
The early volumes of the manga contain stories, plot beats, and visuals that no 11-year-old has any business being subjected to which, of course, makes it all the radder to them when they inevitably encounter it anyway
You've locked those cards away in some ersatz elevator, preventing them from getting out
That artifact gains haste until end of turn
By doubling up this triggered ability, Harmonic Prodigy effectively halves the time it takes for Vivi to reach that sweet spot where you can make enough mana to go off and take control of the game