Shadow Assassin Kayn should some %missing hp to his ult or q or reset e cd on kill/assist
at the moment if you go shadow assassin mode on kayn, your Q and R give no bonus damage. However, if you go Rhaast mode, your Q and R give additional %max hp damage that scales with ad.
It's a bit silly that the tankier version of kayn gets more effective damage than the assassin version does
so maybe we can give shadow assassin kayne %missing hp to give more execute power against low health champions and make him more assassiny
we could also reset his shadow step cd on kill/assist to make him get in and get out quickly