Eggs in Magic are artifacts that you crack to obtain something, usually cards or mana, and their history begins all the way back in the Odyssey MTG Set with cards like Darkwater Egg
It is a lot more obvious when to use Oath than Traverse and a lot easier to play with which makes it quite a lot better in the archetype
Though compatible with the game, they are not associated with or officially endorsed by the games creator
Im mostly happy to play this with Rydia or graveyard synergies (i.e., Esper Origins / Summon: Esper Maduin), though its acceptable filler anywhere
And if you happen to pull, with some help from other cards, an infinite combo with infinite extra attacks, Tifa will make sure you untap in all of them (as long as your 7-power beater hits an opponent, of course)
The Un-Sets have always combined two major types of joke card: ones where the joke is told through the card name, flavor or artwork and ones where the joke extends into its actual mechanics