Who cares if you are knocked up.
Dont forget 
throw in an irelia for good measure and maybe some 
Each source of tenacity is applied separately
Full stacks of Legend will give 20% cc reduction, and each proc of perseverance, assuming they stack, reduce that amount by a further 25%. All together, they would reduce a 1 second stun to .8 seconds, then to .6 seconds, then to .45 seconds. Collectively that would be 55% tenacity.
and
grant 25 and 30% reduction respectively, reducing the .45 second stun to .3375. then to 0.23625 seconds.
Now let's jump into URF, getting the 25% tenacity bonus, reducing it to 0.1771875 seconds.
So with every source of tenacity available to a general character, you could get 82.28125 tenacity.
But we aren't a general character, we're an outnumbered
! We get 40% bonus tenacity! That stun on us lasts 0.1063125 seconds, meaning we have, all together, 89.36875 tenacity.
u forgot irelia
Was it confirmed that it stacks multiplicatively? Pretty sure everything from runes and masteries has always been additive.
All stacking %s outside of CDR are multiplicative.
Was it confirmed that it stacks multiplicatively? Pretty sure everything from runes and masteries has always been additive.
even if the runes stacked additive, it would make 45% tenacity for 10 seconds when youre blowing a summoner spell.
only the resistances are explicitly stated to stack for having both summoner spells on cooldown. not too crazy.
i guess at best you could rotate your summoner spells to extend the effect to 20 seconds. but its incredibly unlikely that the 2 runes stack additive, as usually different sources of tenacity stack multiplicative.
I think items have additive stacking:
https://image.prntscr.com/image/zx-gIPsKR4S3h0yWzRkbeQ.png ######This is form the new steraks
I want Riot to clarify everything about tenacity stacking because the wiki doesn't clarify it much.
I think items have additive stacking:
https://image.prntscr.com/image/zx-gIPsKR4S3h0yWzRkbeQ.png ######This is form the new steraks
I want Riot to clarify everything about tenacity stacking because the wiki doesn't clarify it much.
ive seen it, im active in the same thread.
he also said, that its a weird interaction that doesnt (or shouldnt) happen with other tenacity sources, and if it happens its an oversight which intents to correct.
even if some of the tenacity from runes stacks additive right now, dont expect it to stay this way until the system is released.
however, im looking forward to the possibility of 84% tenacity windows with merc treads, steraks, and garens w. hes not a triforce user (usually), so i gess thats the gimmick he gets out of the buff in return.
tenacity stacks multiplicative, and you dont get the tenacity from perseverance twice.
so no.
There's supposed to be a minimum CC duration of like 0.3s. At least that's what Guinsoo told me in 2011, lol