So there's an unproven theory for getting a t7 horse called the Color Theory. What you supposedly would need is: 1. A combination of horses of a combined tier of 10 with the appropriate levels. Calculator here: http://www.blackd.de/horse/ 2. A total color value of 7 of the same color according to the following chart: http://imgur.com/a/DaeiQ#uM909nf 3. Good luck! Remember, this is all just a theory and nothing here is proven. But so far all the confirmed T7 horses have matched the theory.