D-Arc
The D-Arc is a device that is used in the third season of Digimon. It is almost like a digivice in season 1 or a D-3 in season 2. The D-arc is very special because it has the ability to give the tamers' digimon the abilities of other digimon using a blue card. It can also, however, digivolve a digimon.
The Blue Cards are used in season 3 to give the Tamers' Digimon special abilities of other Digimon in a process called a card slash.