Rinse and repeat until 24 packs have been drafted
Blue decks tend to be slow and patient, gradually building up card advantage and other resources until they're ready for the endgame, which is perfect for a midrange-oriented, moderately powerful format like Commander
The unearth casting cost tends to be costed knowing that these are free cards (just like flashback) and gets in the way of really slimy things you might do
Once it resolves, you add one red mana for each card in an opponents hand, that mana sticks around through phases until the end of the turn, and then Inspiring Refrain resuspends itself with another three time counters, letting you cast it again later
Red, in its purity, feels like it can accomplish so many different goals because it alone as a color is so directly tied to a fundamental concept in Magic: damage
Ive also included Urza, Lord High Artificer, a card that mimics Tolarian Academy, and Storm the Vault, which has the potential to become an Academy