Basically a champion's health and attack speed is first determined based on family, certain traits, and whether those traits match the core essence. Then based on the speed of a champion it'll start hitting a randomly determined defensive part with a randomly determined attack part. They get a bonus based on the rarity of part, if it matches their core essence, and if the essence counters the defending part's essence. Then the defender gets a defense bonus based on their core essence and rarity, ect.
I have plans of adding buffs and debuffs like shields, heals, poison, and stuns and such. If people are enjoying this I'll be more motivated to add them all. Plus I can show here the actual behind the scene numbers if you're interested. I tried to make it fair between the different races.