And you may get some extra shinies that you won't find in the Commander precons
To determine the total cost of a spell, start with the mana cost or alternative cost you're paying (such as a flashback cost), add any cost increases (such as kicker costs), then apply any cost reductions (such as that of The Earth Crystal's first ability)
Also, the decks I said it didnt belong to are a narrow band (with the main relevant one being Najeela, the Blade-Blossom)
Tinker Bell has a moderate Strength of 4 and a good Willpower of 5, but it's her two abilities that make her a powerful Glimmer
on the other hand, Cid, Timeless Artificer asks you to go wide while also creating an added draft and deck building incentive (note that there are very few Artificers in the set)
Deharme All in all, card types are a broad topic with lots to discuss