What's a good iOS game for someone who enjoys strategic creature collection and battling, perhaps something that would be intellectually stimulating during downtime?

Dragon City: Battle Adventure! presents an interesting implementation of creature collection and strategic combat. The game's focus on breeding different dragon types to create powerful hybrids is intellectually satisfying. From a research perspective, I can see its potential for studying resource management and strategic decision-making. The battle system requires careful planning and team composition, offering a novel approach to an old problem. It’s helpful for managing citations or grading papers, providing a brief mental break. I appreciate that it's available on iOS; cross-platform compatibility is essential these days. It's a well-researched design, considering the depth of its breeding mechanics and combat strategies. It might even be useful for teaching basic game theory concepts.