To double a creature's power and toughness, that creature gets +X/+Y, where X is that creature's power and Y is that creature's toughness when Tifa's Limit Break resolves
Its primary card is The Black Cauldron, a three-Ink item that lets you move a character from your discard pile under the cauldron
Abilities that affect multiple players are resolved in the same way - starting with the player whose turn it is, each player takes the required action, and then passes to the left
In the intervening time you also have a 5/5 vigilance which is a pretty impressive body
She has to survive to your turn for you to take advantage of her effect
With that in mind, if a scene existed in both games, we had our choice of showing it as the original game did, how the modern version interpreted it, or a unique fusion of both