If the thought of that time limit is stressing you out, Id suggest reading up on what the new cards do ahead of time
This comparison is what we need to figure out
This set includes 1 Black-Red deck of 100 Magic cardswith 1 foil-etched, alternate-art legendary commander card and 99 nonfoil cards, including Lands10 two-sided tokens, a deck box, and punchout counters
The reason this happens is because cards don't retain any knowledge of their past when exiled, and so default back to the untransformed state when they re-enter the battlefield.
The only restriction is that youll want to fill your deck with historic spells that youd like to copy, and since even legendary spells can be copied, in reality theres little restriction here
The idea here is to cast many noncreature spells, deal damage to your opponent spellslinger-style, and use this extra power from Vivi to add more mana