Mathematical "magic," or experiences of beauty and creativity for K-12 mathematics students, can contribute to deepened content understanding. However, creating opportunities for mathematical "magic" in mathematics classrooms has been a challenge for classroom practitioners. To support development of these experiences in classrooms, we deployed a bi-directional support program between a college-level mathematician and an early-career secondary teacher. Based on data collected from this project, we have identified four principles that will promote mathematical "magic." We conclude that mathematicians and early career teachers can work together to a) leverage understandings of the nature of mathematics, b) apply meta-mathematical reasoning, c) share knowledge of content and students across contexts, and d) recognize students' mathematical development to design learning experiences for mathematical "magic."