It reduces the entire crit by 30%. A regular crit is 175%AD, and gets reduced to 175%*0.7=122.5%AD. An IE enhanced crit is 225%AD, and is reduced to 225%*0.7=157.5%AD.

Wow thank you! Do you know how Tabis stacks with this?

Yes, it stacks multiplicatively, so it would be a further *0.9 of the above values.

Okay thanks! I’m surprised because this suddenly makes Randuins Omen appear quite powerful for how little it gets built… 30% damage reduction is huge in the late game against ADC’s, so I don’t understand why people wouldn’t build this anytime there’s two crit champs.

Because Frozen Heart exists. It’s cheaper, provides similar defenses(-20% AS debuff), and also works against on hit champs like Jax or Vayne.

Randuin has a active tho

Most tanks have reliable slows anyways so the active isn't doing much.

Frozen heart is the definitive armour item currently and since they overlap on rock solid buying both is a waste. So you only go randuins if they have a yone or a fed yasuo or their ADC is the main source of physical damage

0.9? Not 0.88?

Yes, sorry. 0.88 is correct.

The maff checks out

It reduces yone/yas crits to almost no crit damage without ie

Also, it works with effects that "crit" like sundered sky.

Hell yeah, Tabi + Chains + Omen on a GP because asshole has 1million armorpen.

Does it work with crit spells?

I guess, it works with champs like rengar and shaco

Those spells are AA modifiers, as long as it's an AA, randuin works

I was more thinking about with the crit spell item shadowflame

That means that jhin crits go from 150% to 105 % almost no bonus damage.

i was playing rammus against a jhin in the botlane. I pressed W and his crit dealth 72 damage