It's one of the most snowbally card-advantage engines in all of Commander
Sure it's only on your turn, but it's not restricted to once per turn

Aang and Katara Aang and La, Ocean's Fury Aang, A Lot to Learn Aang, Air Nomad Aang, Airbending Master Aang, Destined Savior Aang, Master of Elements Aang, Swift Savior Aang, at the Crossroads Aang, the Last Airbender Absolute Virtue Abstruse Archaic Aeon Chronicler All-Seeing Arbiter Animus of Predation Arahbo, Roar of the World Arahbo, the First Fang Argyr, Tidal Spinner Autumn Willow Avatar Aang Avatar Kuruk Avatar Kyoshi Avatar Kyoshi, Earthbender Avatar Roku Avatar Roku, Firebender Avatar Yangchen Avatar of Discord Avatar of Fury Avatar of Growth Avatar of Hope Avatar of Me Avatar of Might Avatar of Slaughter Avatar of Will Avatar of Woe Avatar of the Resolute Body of Knowledge Burning Sun's Avatar Child of Alara Cloud of Darkness Daughter of Autumn Death's Shadow Deity of Scars Demigod of Revenge Deus of Calamity Diluvian Primordial Divinity of Pride Dominus of Fealty Doubtless One East Wind Avatar Ebon Praetor Essence of the Wild Ethereal Champion Evra, Halcyon Witness Excruciator Fell Shepherd Gaea's Liege Gandalf of the Secret Fire Gandalf the Grey Gandalf the White Gandalf, Friend of the Shire Gandalf, Westward Voyager Gandalf, White Rider Ghastlord of Fugue Gishath, Sun's Avatar Godhead of Awe Hades, Sorcerer of Eld Hallowed Spiritkeeper Hand of Justice Heedless One Herald of Leshrac Hogaak, Arisen Necropolis

Self-mill : Gray Slaad (reads like gray salad, right?), Druidic Ritual, Circle of the Land Druid
And in case you forgot, we typically get seven versions of every Standard rare / mythic as a baseline: a regular and a foil printing from boosters, an extended art and an extended art foil from Collector Boosters, a timestamped prerelease promo in foil, and a foil and a non-foil planeswalker stamped version from the Promo Packs
At the beginning of your upkeep, if there are fourteen or more cards in your graveyard, you may transform Emet-Selch