Some mechanics like dredge are built around self-mill and filling the graveyard, with others like delve utilizing milled cards
Zacama, Primal Calamity This card also represents all the dinosaurs in this set, from Ghalta, Primal Hunger to Zetalpa, Primal Dawn
While there are other cards that give Indestructible, they are usually in the form of a different kind of counter and give Indestructible for stuff with those counters
Thats become even easier with the release of two specific cards in Into the Inklands
Activating Yuriko's commander ninjutsu ability isn't the same as casting Yuriko as a spell
The Motherlode, Excavator You generally get a ton of energy when you drop The Motherlode, Excavator later in a Commander game