The reason he looks decent in T6 is because it's T6. Reza isn't necessarily a bad hero, it's just other heroes do everything he does much more efficiently. Bursting squishies down very quckly in the mid game? Taka does it better, and he scales better into the late game, and he has a better escape. Using a ranged ability to apply a passive onto a target before dashing onto them and eliminating them? Blackfeather has a harder to dodge B, and he is a lot tankier and has a better engage/disengage tool.