First off I don't believe
ever had Tenacity. He had a speed debuff clear but if he was stunned he was still stunned. Hard CC was able to keep him down.
Now onto what you're talking about with Irelia. She has a passive tenacity of 10% facing one champion, 25% against two and 40% for three or more.
**Tenacity as a Mechanic on
**
Now not sure if its common knowledge but for those that don't know Tenacity is multiplicative buff over an additive one.
This means that if she has Mercury Treads
which grants her "Reduces the duration of stuns, slows, taunts, fears, silences, blinds, polymorphs, and immobilizes by 35%" then her total Tenacity is 41.5% or 42% for the sake of simplicity instead of 45%. Not much of a debuff here but its important because she should never be able to reach 100% tenacity and when she faces 3 or more champions her tenacity isn't 75% but rather 61%.
At max Irelia can have the highest recorded Tenacity in game at 70.7% and maybe slightly more towards specific things like slows with masteries.
This means she is able to accomplish her goal of assassination without much able to slow her down for long.
How to counter someone like Irelia
Irelia's not the only champion like this however she is the only champion who is able to maintain such a high resistance for a prolonged period of time.
is able to completely ignore all forms of CC with his ultimate in order to deal damage or run away without much to stop him but Irelia will still take 20-30% of the effects. Though not much it does mean that consistent application affects her. So one way to counter her Tenacity would be someone who can slow her consistently like
's new passive but without it being Ashe. So a
can help with the application but at max Tenacity will only slow her for about .4 seconds for 40% of her movement speed which means the application needs to happen twice a second to be significant meaning an attack speed of 2.0 or higher. You can see why that's not very useful right? At 2.0 she still has .2 seconds of free time to try and run off and if you're not fast enough to keep up she'll get away or stun you before wrecking your day or making her escape but the advantage her is that she only has .2 seconds if 3 champions are around. If its 2 champions or less and the application is happening twice a second she should be consistently slowed. But slowing her doesn't mean burst and in a team fight the situation is hardly that ideal.
So then what does one do to deal with her? The problem is to deal with Irelia you need someone that can eat past her defenses quickly. Its all about burst against her and an Olaf with his ult up. If you can do more damage than either of them is able to lifesteal away you've got them.
But there is one more important factor, Tenacity doesn't reduce Suppression, Knock Ups, Knock Backs or
's ultimate.
So if you need to CC Irelia your best bet is getting her caught in either
,
,
,
,
,
,
,
's ultimate's or use a knock up from
,
,
,
or
.
Just remember if you use
's ultimate support him by either being in his ring or firing outside her range because if you're too close she'll escape and probably wreck your ADC.
As an ADC however... you're unfortunately at the mercy of your team to protect you as there is little you can do to deal with an Irelia once she's jumped on you.
The last thing I can think to add is that persistent slow fields should reapply fast enough to affect her despite her Tenacity but those only work until she walks off of them which doesn't take much effort with her Q.
I understand she's infuriating, but remember she's not the only champion that can go straight for your carry in a fight. A Fizz or Leblanc to some extent are able to bypass the team and go straight for the carry as well. It all depends on positioning and if you play the carry i suggest keeping an eye on Irelia and asking your team to prioritize her if she's become that much of a threat.