Elsa has a resource cost of 3, attack power of 2 and a defense rating of 3
Add to this the initial stock problems Ravensburger faced, and its clear why these cards are so prized
Cid, Timeless Artificer Cid, Timeless Artificer is an interesting build-around that I imagine comes in two flavors: You either go hard on looting, cycling, and self-mill to throw multiple copies of Cid in the graveyard, or you do some Mirror Box shenanigans
Not only do you need to be consistently attacking with your Commander or blinking it to get the most out of this enchantment, you also need a high density of legends in your deck to maximize the effect
either your opponent finds themselves unable to block due to a lack of flyers on their board, or they get their flyers wiped out one by one by deathtouch