Planeswalker cards are a special type of card in the trading card game Magic: The Gathering. They represent powerful allies that players can summon to aid them in battle. Each planeswalker has a unique set of abilities and a starting number of loyalty points, which can be increased or decreased by using their abilities. Players can activate a planeswalker's abilities once per turn, allowing them to cast spells, create creatures, or gain other advantages. If a planeswalker's loyalty points drop to zero, they are put into the graveyard, making strategic use of their abilities essential for success in the game.