This study presents the technical design, implementation, and evaluation of an AI-powered debate bot integrated into a Globally Networked Learning (GNL) course, which connected 97 undergraduate students from Germany and the United States. Unlike traditional AI applications in education that focus on content generation or information retrieval, our debate bot was specifically engineered to challenge students' thinking through structured argumentation about the United Nations' Sustainable Development Goals (SDGs). Through careful prompt engineering and system design, we created an AI system that functions as a Socratic sparring partner, pushing students to defend their positions with evidence-based reasoning. Our mixed-methods evaluation revealed that 60% of participants reported a positive impact on research memos, 52% revised their memos with more evidence-based claims, and 32% considered alternative perspectives about their SDG. Notably, the bot played a significant role as a cultural intermediary in international collaborations, creating a "safe third space" for cross-cultural dialogue. This paper provides detailed technical specifications, prompt engineering strategies, and implementation guidelines for educators seeking to leverage AI as a catalyst for critical thinking rather than a shortcut for content generation. Our findings suggest that when thoughtfully designed, AI debate systems can promote the metacognitive reflection and analytical rigor essential for 21st-century global competencies.