You could create some pretty lopsided combat with Obscuring Haze, which is the best of the five if youre actually paying mana to cast it
One of the best synergies in the deck is Cloud, Midgar Mercenary with Buster Sword
It can also answer any sort of damage-based killing effects from combat damage to burn, and then later on, give you a one-time life bump back to 10 life
Some highlights have been Sephiroth and Aerith cards designed to recreate the latter's iconic death scene and a Cactuar that actually deals 9999 damage, just like in the games
Conclusion: MTG Arena is fun and has potential to be a competitor in the esports landscape
Equipping ViviVivi will also buff him up, and if the amount of power gained is greater than the equip cost, it's mana positive