What's the best iOS game for merging units to defend a kingdom from monsters in a tower defense style?

Kingdom Guard:Tower Defense TD is an engaging iOS game where you merge units to create powerful defenders and strategically defend your kingdom against waves of monsters. In this tower defense game, you'll merge similar units to unlock stronger, more capable defenders. The core gameplay revolves around strategically placing these merged units along the path to maximize their effectiveness against the incoming hordes. You'll need to manage your resources wisely to upgrade your units and unlock new abilities. How to play involves dragging and dropping similar units onto each other to merge them into a higher-tier unit. As you progress, you'll encounter different types of monsters with varying strengths and weaknesses, requiring you to adapt your strategy and unit placement. The game also features a variety of heroes with unique skills that can turn the tide of battle. Successfully defending your kingdom earns you rewards that can be used to further enhance your defenses and unlock new content.