Attack Speed slows

Playing marksman against a Frozen Heart and Randuins/Thornmail tank is a pain in the ass, with the exception of Caitlyn (outranging frozen heart) every marksman looses 30% attack speed when hitting them. That is already a massive amount, considering that many marksman get above 2.0 attacks (=being reduced to 1.4). But then add a Nasus Wither to that equation and it is a 75% attack speed slow at the end of Wither. I played Ashe with Lethal Tempo and got close to 3.0 attacks with Lethal Tempo and my Q active. I was not able to attack him or kite because I was slowed to the minimum movement speed and my attack speed was close to 1.0. It was impossible for me to kite him being permanently slowed down, I could not life steal sustain because I could not attack him and relying on my passive slow is kinda pointless against a Wither.