So uh... why exactly do Zyra's plants and Azir's soldiers get the 40% slow out of Rylai's?
Seriously. Like, Azir's soldiers I could maybe understand, cuz they're sorta not summoned minions (i mean, they pretty much are, but they're not targetable) but really even if they're not 'summoned minions' they're still certainly 'multi-hit' and should therefore be 20% on those grounds. Not to mention just for the sake of balance they shouldn't get the strong slow.
But Zyra's? By no means should they have ever gotten a 40% slow. They're clearly minions, not to mention 'multi-hit', yet for some reason they get to have the single-target slow. Cuz, you know, Zyra isn't already a giant middle finger to melees without getting a 40% permaslow from her plants.
Idk if there's any other minions getting preferential treatment, I haven't bothered to test them all, but I have at least seen that Malzahar's are treated properly and only get the 20% slow. I haven't really noticed feeling excessively-slowed by any other minions in my games (unlike with these two, which prompted me to finally test for myself), so I'm assuming these are the only two.
*Addendum: tested out with Annie/Tibbers too, 20% slow for them (well, her ult gets 40% for 1 second on the initial cast cuz the upfront burst, but it's 20% from Tibbers himself).
Tested out with Heimer too, his turret's regular attacks get 20%, but the beams and everything his ult turret does gets the 40%... kinda questionable as well, but at least it's more conditional for him and not 100% uptime.
Also, since a lot of people seem to misunderstand: Multi-hit =/= multi-target/aoe. Multi-hit means the skill can hit a given target multiple times with a single use, kinda like damage over time, though not necessarily with the same periodic nature.
Whether or not Azir's soldiers are really summoned minions, they ARE pretty undeniably able to get multiple hits out of a single ability use, so yeah, they really ought to get the '20% for 1 second" slow that multi-hit/dot abilities and summoned minions both are supposed to get.
or
the plants and soldiers can't run down people on their own and keep a long term slow on them, which is why those spells got 20% slows in the first place.