They typically offer a single effect performed by playing and discarding the item
When you cast this spell, create X 0/1 red Kobold creature tokens named Kobolds of Kher Keep, where X is the amount of mana spent to cast Prossh.Flying.Sacrifice another creature: Prossh, Skyraider of Kher gets +1/+0 until end of turn
Reforge the Soul, Dark Deal, and even Dragon Mage are good wheel effects, and you can combine them with the likes of Megrim, Liliana's Caress, or Sheoldred, the Apocalypse
Blade of Selves is hands-down the best, since it gives any equipped creature myriadparticularly nice to give to something like Tormented Soul that cant be blocked
Tom Bombadil Tom Bombadil allows you to build a deck around all the best saga cards
More details on Final Fantasy's unique cards and mechanics are expected in May