Cunning Black Strategist is another term used to describe the meme "You Just Activated My Trap Card!" For those who don’t know what a trap card is, it is a card in the popular game based on Yuh-Gi-Oh. There are numerous parodies of Yuh-Gi-Oh card playing, but this one focuses on a black man sitting at a table, holding up a fan of cards from the game.
The man has a look that in the meme world could be best described as "PWNED". In other words, the look conveys that the opponent has made a fatal card-playing mistake and the man is about to take him down and win the game. This man is referred to as "The Playa".
The purpose of a Trap card in the game is to be used during a duel, and allows the player (or Playa) to do much better in the duel while the opponent does much worse. In general terms, the popular culture reference to a trap card implies that doom of some kind is imminent while success is close at hand for the person throwing down the proverbial trap card.
The meme shows the smugly-grinning black man at the table, holding his fan of cards in one hand and in the other hand, he holds a single card which is quite obviously the Trap card. He is just about to throw it down. For this meme, the original variant of it is simply labeled ""You Just Activated My Trap Card!"
There are other variations of this meme, utilizing the phrase "You Just Activated My Trap Card!" or some variation thereof. There is also one form of it in motivational poster format with the tagline: "My Trap Card. You Just Activated It".