The Crystals depicted on the MTG crossover cards are specifically from Final Fantasy III , which featured a timeline where the four elemental crystals all had dark counterparts (represented solely by The Darkness Crystal)
Each player begins with a deck of cards, drawing from it to play characters, cast spells, and activate special abilities
The Emblem art is more familiar, being the same Tetsuya Nomura piece seen on the Borderless version of the main set Sephiroth
Izzet Prowess (140 players) : The deck lives up to its name, applying early pressure with Stormchaser's Talent and Cori-Steel Cutter, often flanked by Monastery Swiftspear and Drake Hatcher
Final Fantasy X is a favorite of mine and Zakeel, the FIN Product Architect, so we were a little biased in choosing it