Its artwork is crystalized to show it's Terastalized
Field Spells have a dedicated zone, the Field Zone, and consequently each player may only have one Field Spell active at a time
Their main weakness is mana cost, but with proper ramp and fixing, Dragon decks perform well at casual and mid-to-high power Commander tables
You can even recycle your Spell cards on your turn, allowing for Magician Of Black Chaos MAX to build you a ton of advantage
Since the Final Fantasy decks are pretty new, anyone who hasn't been testing them ahead of time online through unofficial channels like Tabletop Simulator or Cockatrice likely hasn't gotten a good idea of how well each deck plays just yet
Now, that will take work and a good deal of market research but its definitely possible