The combination of mana cost, stats, enchantment typing and two powerhouse abilities make this almost as universal as Setessan Champion, and four of each is a decent place to start green Standard lists if you want to do anything with enchantments going forward
It sounds simple, but it completely shuts down the haste-based racing decks and disrupts the artifact mana rocks that Ramp decks rely on
Hellkite Courser is particularly bonkers with The Ur-Dragon since its whenever one or more Dragons you control attack trigger is amazingly powerful, as befitting a nine-mana Dragon Avatar
I am a big fan of lifelink in Commander these days, and Metamorphosis Fanatic is my kind of card
Very cool stuff, and a great way to play with the cards with other people
(with purchase of any booster box) Bend the elements