The 4-of-a-unique-card limit was a formative rule for constructed Magic issued on high with the first mandatory tournament rules, along with 60 card minimums and 15 card sideboards
This deck actually has a unique feature in its release for the commanders: Its backup commander is a Spacecraft, Inspirit, Flagship VesselInspirit, Flagship Vessel
To stay on track here, I won't consider the old lifelink, so more Unflinching Courage, less Armadillo Cloak
It relies on getting graveyard value out of Sefris and Sun Titan, plus extra dungeon triggers from Hama Pashar, Ruin Seeker
MOM has a bonus sheet, Multiversal Legends (MUL), consisting of reprints of legendary creatures, some of which (like Atraxa, Praetors' Voice or Ragavan, Nimble Pilferer) are long-time MTG staples
Its good despite being sorcery, in formats where you have accelerants like the moxen or Ancient Tomb, and especially in singleton-heavy formats like Cube, Commander, and Vintage