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
For example, an ability that triggers "whenever you sacrifice a creature" triggers only once
Instead of playing Vivi as a pure spellslinger commander, players can instead build a Voltron deck around him, buffing him with items and enchantments until he has enough power to deal a devastating board wipe or completely wipe out all other opponents
And we haven't even considered Eerie triggers at this point
ETB/flicker decks rely on their creatures to deal with artifacts/enchantments, so Torpor Orb could lock a deck like that out of the game
But even if you miss out on that, Mishra's Foundry will be in the set as well, in both normal and extended-art form