One of the founding fathers of Magic writing and theory was Eric Taylor, who defined it like this: "Card advantage is any process by which a player obtains effectively more cards than his opponent." If that definition seems a bit nebulous, it's because card advantage can take such a tremendous variety of forms
It's also good in tribal Snake decks built around Kaseto, Orochi Archmage or Seshiro the Anointed
Rather, its more of whether it will fit within your meta and against your opponents
The Duels series did not feature full sets of Magic cards but selected subsets, and were initially designed to couple a challenging single-player experience with an advanced artificial-intelligence computer opponent
Plus, things like Eldrazi Temple, Urza's Mine, Urza's Power Plant, and Urza's Tower for even more top-end and explosivness