Storyborn characters are the most well-known version of a character, while Dreamborn might alter an aspect or two
At worst you get stronger and stronger creatures
For instance, the Final Fantasy 14-based Scions & Spellcraft deck is mostly concerned with casting non-creature spells, but packs in too many creatures representing the games characters
This lets all players mill three cards at the start of each upkeep, one of which can be removed from play, after which the Kin becomes a copy of that card
Eldrazi Conscription is also a strong card in decks that want to cast big, colorless Eldrazi spells for cascade or other benefits
The main thing to keep in mind is that you can't remove finality counters from Hexavus itself, so its a bit vulnerable to the same counter you're using it to remove