The previous wave of courses was released in December and added beloved Mario Kart tracks to the Switch game, including Maple Treeway from Mario Kart Wii and Rainbow Road from Mario Kart 7.
More importantly, Mario Kart 8 Deluxe will feature 100% more Birdo. After making an appearance in Mario Kart: Double Dash for the Nintendo GameCube, Birdo makes her illustrious comeback to the Mario Kart franchise. As part of the Booster Course Pass DLC, she is the first new character to be added. Wave 4 of the Booster Course Pass will also include seven additional, unannounced courses.
The Booster Course Pass for Mario Kart 8 Deluxe is available from the Nintendo eShop for $24.99. The pass is also included in the Nintendo Switch Online + Expansion Pack, which has an annual cost of $79.99 for a family plan and $49.99 for individuals.