My own idea would be having a unit that's designed to potentially be all-solving, with a Piercing or Magic AoE attack to run over most possible threats to it, something crazy like 3k effective HP after the block of armor, but costing a truly vast amount of resources and, owing to its damage type, being basically useless to deal with structures. And Medium armor units of considerable bulk. Flaws dealt with via a cargo capacity and Burrow functionality, allowing a game-ending move of getting three of them fully loaded with Siege units, then having them fly into the enemy base to lay waste to everything that could be sent in response. At a total cost of some 80 food for three bodies, maybe, and easily 3k resources.