Indeed another Sphinx of the Consecrated variety this time is very much the way to go if you want value and snowballing power
At least from an MTG perspective, this puts Sin alongside graveyard commanders like Muldrotha, the Gravetide, but with the chaotic twist of that aforementioned cycle
Constantly dealing instants and sorceries not only provides you with a great opportunity to buff Vivi with +1/+1 counters (and chip away at your opponents health total), but also provides you a boost to your mana pool meaning you can afford to cast even more spells
The ability of MJ, Rising Star triggers just once for each life-gaining event, regardless of how much life is gained
You don't choose a target for Espers to Magicite at the time you cast it
Not much more is known at this time, but Final Fantasys rich history is full of places to draw inspiration from