Im a fan of the idea of playing it in a deck that runs creatures with echo, like Karmic Guide and Bone Shredder, building a cool recursive engine
There are decks out there that simply have no hope of overcoming that amount of life gain, and Heroes' Reunion cast repeatedly can bury them
These let us dig deeper, and reset our mana to keep our engine spinning
A "legendary source" is a permanent, spell, or card in any zone with the supertype "legendary." Notably, a creature that becomes legendary due to Coronation of the Wilds is a legendary source
3 Narfi, Betrayer King The first real Snow-based Commander that cares about your Snow permanents, even if it's just creatures
(Well maybe for a little while, but as the Twilight Zone has taught us, never for very long.) Anyway, R&D realized that it annoyed players so we consciously chose to dial it back