Queen captures on C 4 with checkmate.
Most of these Chessmons have an effect upon deletion, kind of like little bombs of value when they pop. Hence, c4.
The boss of this deck is Cendrillmon (EX7-030), and is our Queen.
Her overclock deletes one of our (usually) Chessmon in order to activate Overclock. Hence, she captures our c4.
Overclock is a great way of getting some extra reach in the deck, allowing us to give something a total of -12,000 DP on her attack trigger alone, as well as to hit for another security or for the game, ending in a checkmate.
QxC4#