Weekly reminder that Karthus's Interaction with Luden's Echo effects is still confusing

We've got Luden's, Runic Echoes, and now Astral Comet (and maybe Predator, I'm not sure on that one) that while they work fine on most other champions, nobody really knows how it works on Karthus and his Ult. I've heard 4 different theories at this point as to how the effect works on Karthus's ult:

1. Whoever is closest to Karthus
2. Whoever is currently top of your scoreboard
3. Whoever was First pick in Champ select
4. Whoever is closest to your Cursor

There are so many theories at this point, that I'm about to start making this a meme where people come up with random ways the effect procs like "Whoever bought boots first" or "Whoever is closest to Dragon/Baron" or something like that lol.

I just want there to be a way where I can CLEARLY see who's going to be hit with the luden's proc when I ult as Karthus. And if I may be so greedy, I'd also like to CHOOSE who I'm proccing with the ult to add more choice to the matter. I know that riot doesn't really like RNG in this form, so maybe if they read it we can change it so that it's a bit more healthy. :)