You might want to focus on removal spells (like [c]Fateful Absence[/c]), counterspells (like [c]Saw It Coming[/c]), and board clears (like [c]Doomskar[/c])
Black Lotus has become infamous as a symbol of the early, unbalanced nature of Magic: The Gathering rules
As an example, let's take the legendary Boris Devilboon, whose rules text reads: "2BR[T]: Put a minor demon token into play
It's somewhat reliant on your opponents playing creatures, though that's a small hurdle in most games
However, Sneak Attack-ing in a card from your library is no joke, especially when you get the creature back into your hand rather than your graveyard
In a small defense of digital-only cards, its something that only digital games like MTG Arena or Hearthstone allow you to do (although you could try to make this work in paper)