Like most Magic: The Gathering cards, the value of Stormscale Scion depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Tarkir: Dragonstorm)
Lastly, there are tokens , representing permanents that aren't part of their owner's deck
The card selection in the set is generally pretty strong
Probably less so when you see the artwork
Perhaps you dont want a powerful Pokemon knocked out, or you want to get all the Energy and Held Items back into your hand for redistribution
You will be copying your Saga creatures, and can take advantage of any of the Saga's effects since you can choose to put any number of lore counters on it between one and three