You decide whether to have Valakut deal damage to that permanent or player as the ability resolves
So, if you've dropped an Impervious Greatwurm or Krosan Cloudscraper this turn, you can immediately double its power and attack with it for devastating damage
Interestingly, Mark Rosewater (Head Designer for Magic: The Gathering) notes that sagas were brought back because they meshed well with the comic-book panel-style storytelling, allowing players to follow each subsequent saga effect in a new illustrated panel
Against fair decks this is well worth it but against a combo deck where it is just a pure race this massive momentum swing can be too late
Yes, its a little pricey for Modern, but no more than other control finishers like Teferi, Hero of Dominaria
For example, if you control a Flame Channeler and an effect creates a token that's a copy of it, the resulting permanent is a transforming double-faced token that is a copy of Flame Channeler
