The Black Triangle error Base Set Booster Pack is a rare and collectible mistake from the early days of the Trading Card Game. These packs originally had a "1st Edition" stamp, but the stamp was covered with a black triangle to designate them as Unlimited Edition. The black triangle variant was produced for a short time, making them highly sought after by collectors due to their rarity and the historical significance of the production error. Despite the error, the cards inside are standard Base Set Unlimited cards.