Invincible Hymn - This is not a normal Boros finisher, but it can swing your life total so far out of reach that aggressive decks may have a hard time finishing you off
At the beginning of each opponent's upkeep, if that player has no cards in hand and this enchantment has two or more quest counters on it, you may have that player lose 5 life
Secondly, I genuinely feel that you can build a deck in such a way that the Fervor ability is worth closer to a full cards worth of value than one would think
Easily seen but contained, not deep
So, the only real hoops you need to jump through for Kona to cheat something devastating into play besides having the card in your hand is to tap this card and have it survive to your second main phase
Then again, Phantasmal Image has seen a number of reprints that have helped bring its price down, so it's possible Flesh Duplicate has a way to go yet before the price spike is over