That's where Fallout s Agent Frank Horrigan comes smashing in as a massive Golgari commander with a double proliferate trigger
Again, it's not card advantage in and of itself (since you draw three, and then discard three + lose the Coliseum), but it combines famously with Deep Analysis and madness cards (such as Circular Logic), and its effect can't be counterspelled
You will likely have enough for two dual-element decks if you run 20 Sites per deck (below the current official minimum), but you probably wont have enough for a legal constructed deck with 30 Sites
And if we have decent enough excuses for three of them, it's not like we're gonna leave Phoenix Heart hanging
Most Commander decks try to circumvent the singleton aspect of the format by including cards to recur things from the yard
It has tons of interesting lands with powerful abilities