One other subtle strength here is the degree of control you can have over exactly when cards are milled, and how many (assuming you have painlands or other unrestricted self-damage sources)
Akiri, Line-Slinger is your first partner, a two-mana commander with first strike and vigilance and whose power is entirely dependent on how many artifacts you control
Now six mana is expensive and you have to wait for the next upkeep to trigger it but switching life totals with the opponent while we have 0 or less is about as game winning as it gets
Theyre one of blacks characteristic creature types, which means they show up in just about every new MTG set
Minn, Wily Illusionist Its lovely to go wide with creature tokens, but why not have them build off each other
It can always come back to the battlefield so long as you have the six mana to pay for the ability, and can be done at instant speed, letting you use any unused mana to bring it back so you have it on your battlefield before your turn starts