From Bulbapedia, the community-driven Pokémon encyclopedia.
Entercards (Japanese: エンターカード Entercard) are an item introduced in Pokémon Mystery Dungeon: Gates to Infinity. They are initially seen in possession of Umbreon and Espeon, who explain that the Entercards utilize the power of ley lines to open up a Magnagate as a means-of-transportation or entrance to a dungeon. By using different combinations of crafted Entercards, they change the flow of ley lines and force them into new patterns. Although technically unobtainable as a bag item by the player, the partner Pokémon briefly has them in their possession. Keldeo also made Entercards to guide the player and their team to Glacier Palace.