The cards and packs you earn and purchase in game are locked to your account and cannot be traded, but the packs you gain from purchasing physical packs and winning tournaments are tradeable, meaning packs are the primary currency in PTCGO
Aristocrats is at its best in the RWB color spectrum, with black providing the best sacrifice effects and payoffs, and white providing the token generation and creature fodder needed for the strategy
Or a kraken for that matter
Nowadays, there are multiple other answers just as efficient as Fatal Push like Prismatic Ending and Unholy Heat, and the card has been slowly replaced with these alternatives as they are just more versatile
I also love creatures that sacrifice themselves for value, like Selfless Spirit, Bulwark Ox, and Cathar Commando, for the deck