Now, how is that PSA/newsworthy?
Well, enemies debuffed by 
count as being slowed.
: 4% current HP per second on **slowed **targets.
Oppression mastery: 3% less damage from slowed enemies.
Meaning, if you plan on grabbing a FH, you might as well think about bringing Oppression. And if you buy a FH and have a way of continually stacking it, you might also think about Liandry's.
Sire Hippington2 voteshave u anny proof for this? usually AS-slow is not seen as a slow, Yi for example gets slowimune duering ult, but FH still slows his Attackspeed.
also, and oppresion say movment-impared enemys, which as doesn't count for.
edit: thx for the news
EffectFX1 votesI'm 99% positive Yi iin his ult doesn't have his attack speed slowed anymore.
ProfDrDeath1 votesTested it on PBE (for FH at least). On the 4.20 patch, too.
Fed by Snu Snu1 votesWhat the OP says is legit and indeed works that way, you can playtest it.
Rebonack2 voteshave u anny proof for this? usually AS-slow is not seen as a slow, Yi for example gets slowimune duering ult, but FH still slows his Attackspeed. also,
This used to be true, but it isn't any longer. Riot fixed it a while ago. Now if Yi is in Frozen Heart range CANNOTBESLOWED is going to be spamming above his head.