The self-locking lid keeps your cards securely stored when not in use, while also offering easy access
As such, if Vivi has the power for it, it's better to use Vivi's effect for mana rather than from lands or mana rocks to cast spells on your turn
That means it should be given away for free when you join the league
With Lifelink, youll be able to buffer your life total significantly, assuming your creature is also big
With over 50 million HP, it takes well over an hour to defeat it, even with a high level party
Meaning that if you can stack your field right, your opponent is going to have to either let her remain on the field, gathering you Lore points, or sacrifice a character they could have been using to do literally anything else to get her off the field