Hello, thanks for your feedback!
I've got an idea to outplay pesky ponies out there. I know he's just steamrolling into your harmonic illuminati safety zone, but I think he can be stopped, or at least slowed by a grenade shoved in his face. If you meet another Hecarim as Heimerdinger, with vision kept ready you may have a chance to stop him from ruining your fun. I hope it helps, I haven't encountered this problem lately as I'm just warding my way out of bronze in ranked flex with Karma support, but this is the best I can provide at the moment. Hope it helps.

I know about Athene's changes and I'm working on an update, be patient, as I will remove Athene's and replace it with Morello. By the way, the build order and a lot more things need to be changed, so I'm on my way to do these.

Follow-up:
I finally edited stuff I wanted to change. Liandry's is a good magic pen item of course, you can try it if you want, but Heimer's abilities are not that kind of damage over time abilites, your rockets' damage is high enough to oneshot an adc with bt, so I would not build that. I will give it a shot, and update this reply again so I can give a bit more advice.