Lancer is a main character from the game Deltarune.  A Darkner like Spamton, Ralsei, and Jevil, Lancer is white and black with blue details including and looks like a spade from a deck of cards.  For your costume, you can start with a white full-body suit.  Wear a blue hood, blue gloves, and blue shoes.  Add an iron-on blue spade decal to a black leotard to wear over top and you're ready to go.

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