Undertale characters, Deltarune characters, crossover, pixel art style, battle scene, colorful magic effects, heart motifs, determination, friendship themes, underground setting, fantasy forest background, 8-bit music notes, retro video game aesthetic, dynamic poses, action-packed, Frisk determined face, Kris with sword, Ralsei casting spell, Susie with axe, Toriel protective stance, Asgore majestic, Lancer mischievous grin, Papyrus doing a cool pose, Sans with a wink, Chara with a knife, full scene composition, vibrant lighting, digital art, sprite showdown, fan art concept, creative interpretation, engaging fight, detailed expressions, character interaction, iconic symbols, determination soul, save point, pixelated textures.