It doesn't matter what percentage it is, it's the fact that there's an automated execute in the first place. The fact that it's 20% just makes it even more ridiculous. You don't automatically get executed at 100% just for existing near someone with Elder buff. I don't get what's so hard to understand tbh.
An automated execute that you don't have to actively interact with aside from killing Elder to gain the buff is just bad game design in general. You can't really play around it aside from waiting it out or avoiding a fight unless you want to give up objectives/map control for free, but that's not always possible. That's what I'm getting at.
I honestly can't believe it was implemented in the first place or why some seem to be okay with it, but this is reddit after all; biggest echo chamber on the internet.
Tell me why you think Sivir deserved to die completely off-screen to something she can't counter aside from running away (which clearly didn't even work), or why Galio deserved to be executed while Zac was in blob form. Because they had the audacity to try and fight a single enemy champ trying to take down their inhib? I'm honestly not trying to discredit the Zac in any way, more so pointing out how ridiculous the execute "mechanic" is.