Rebirth, like Remake before it, has a bunch of summon materia you can get from your in-game companion Chadley and equip to boost your stats while also giving you the ability to summon powerful creatures to your aid during battle.
You'll also need to free around 150 GB of storage space as well. And if you want to head out into the wide open world of FF7 with all possible materia, you'll need to have a save file from the previous games, as well as have pre-ordered the correct edition.
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