RIP AP Tristana

Dear Riot, I believe that by nerfing Tristana's ultimate in patch 4.17, you have effectively destroyed AP Tristana. AP Tristana desperately needs her ultimate to have assassination potential, and now the cooldown is way out of line with other assassins'. Leblanc's "Mimic" starts at just 40 seconds. Talon's "Shadow Assault" is 75. Akali gains an "Essence of Shadow" every 30 seconds. Katarina's "Death Lotus" has a cooldown of just 60. Let's not even mention Riftwalk. Of course, there are other assassins whose ultimate's' have higher cooldowns, such as Zed and Ahri. However, these ultimates have much higher utility than AP Tristana's. Zed's ultimate grant's untargetablilty, and sets up major jukes. Ahri's also allows for incredible repositioning. The knock-back on Tristana's ultimate is useless when she is building AP, as the ability is almost always used to end an assassination, not for utility. Now, having established that Tristana's ultimate's cooldown is way out of line with the norm for assassins, I would like to offer a couple suggestions. Simply changing the cooldown to 90/75/60 would help dramatically. This would line up the cooldown of her ultimate with the cooldown of Deathfire Grasp, and enable her to be more effective. If Riot is set that her cooldown must be longer, perhaps they could raise the slow on her W, as it is pitiful in its current state. I appreciate the fact that AD Tristana is too strong, but it is incredibly infuriating to see that Riot appears to not even have considered the effect on AP Tristana. They don't even mention looking out for her in the 4.17 patch notes. If there is anything you could do to help out AP Tristana it would be greatly appreciated. I love playing her and it is really frustrating to see a fine midlaner be nerfed into the ground.