Its first chapter provides a situational Oblivion RingOblivion Ring, its next two chapters provide a temporary PropagandaPropaganda to help thwart go-wide strategies, and its final chapter lets you net some Treasure tokens so long as at least one of your opponents has a creature with power four or greater
Unlike mill, however, lifegain is rather popular
They use the stack and can be responded to
Its also interesting to note that Tifa itself can deal 7 combat damage due to melee if you attack each other player (Cadric, Soul Kindler plus myriad, anyone?)
It also gets its own removal spell if you pay 7 and transform it into Hydaelyn, the Mothercrystal
A spell cast using flashback will always be exiled afterward, whether it resolves, is countered, or leaves the stack in some other way