Can kalista get a quality of life change for her "E" (Rend) to let the player know when it will kill

I find it very difficult playing kalista to know how much damage Rend will deal on activation, i feel like just making a gray bar over their HP that lets the player know how much rend will deal would make playing Kalista easier for knowing when to use Rend for a kill rather than just guess. I feel that when you consider that if you use rend too early it goes on quite a long cool down vs when you kill them it will reset the cool down a simple meter will adequately fix the nerviousness some players feel about using Rend